Apparatus and method for measuring optical characteristics of an object

ABSTRACT

Optical characteristic measuring systems and methods such as for determining the color or other optical characteristics of teeth are disclosed. Perimeter receiver fiber optics are spaced apart from a source fiber optic and receive light from the surface of the object/tooth being measured. Light from the perimeter fiber optics pass to a variety of filters. The system utilizes the perimeter receiver fiber optics to determine information regarding the height and angle of the probe with respect to the object/tooth being measured. Under processor control, the optical characteristics measurement may be made at a predetermined height and angle. Various color spectral photometer arrangements are disclosed. Translucency, fluorescence, gloss and/or surface texture data also may be obtained. Audio feedback may be provided to guide operator use of the system. The probe may have a removable or shielded tip for contamination prevention. A method of producing dental prostheses based on measured data also is disclosed. Measured data also may be stored and/or organized as part of a patient data base.

This application is a continuation of application Ser. No. 08/886,564filed on Jul. 1, 1997 now U.S. Pat. No. 5,880,826.

FIELD OF THE INVENTION

The present invention relates to devices and methods for measuringoptical characteristics such as color spectrums, translucence, gloss,and other characteristics of objects such as teeth, and moreparticularly to devices and methods for measuring the color and otheroptical characteristics of teeth or other objects or surfaces with ahand-held probe that presents minimal problems with height or angulardependencies.

BACKGROUND OF THE INVENTION

A need has been recognized for devices and methods of measuring thecolor or other optical characteristics of teeth and other objects in thefield of dentistry. Various color measuring devices such asspectrophotometers and colorimeters are known in the art. To understandthe limitations of such conventional devices, it is helpful tounderstand certain principles relating to color. Without being bound bytheory, Applicants provide the following discussion. In the discussionherein, reference is made to an “object,” “material,” “surface,” etc.,and it should be understood that in general such discussion may includeteeth as the “object,” “material,” “surface,” etc.

The color of an object determines the manner in which light is reflectedfrom the object. When light is incident upon an object, the reflectedlight will vary in intensity and wavelength dependent upon the color ofthe object. Thus, a red object will reflect red light with a greaterintensity than a blue or a green object, and correspondingly a greenobject will reflect green light with a greater intensity than a red orblue object.

The optical properties of an object are also affected by the manner inwhich light is reflected from the surface. Glossy objects, those thatreflect light specularly such as mirrors or other highly polishedsurfaces, reflect light differently than diffuse objects or those thatreflect light in all directions, such as the reflection from a rough orotherwise non-polished surface. Although both objects may have the samecolor and exhibit the same reflectance or absorption optical spectralresponses, their appearances differ because of the manner in which theyreflect light.

Additionally, many objects may be translucent or have semi-translucentsurfaces or thin layers covering their surfaces. Examples of suchmaterials are teeth, which have a complicated structure consisting of anouter enamel layer and an inner dentin layer. The outer enamel layer issemitranslucent. The inner layers are also translucent to a greater orlesser degree. Such materials and objects also appear different fromobjects that are opaque, even though they may be the same color becauseof the manner in which they can propagate light in the translucent layerand emit the light ray displaced from its point of entry.

One method of quantifying the color of an object is to illuminate itwith broad band spectrum or “white” light, and measure the spectralproperties of the reflected light over the entire visible spectrum andcompare the reflected spectrum with the incident light spectrum. Suchinstruments typically require a broad band spectrophotometer, whichgenerally are expensive, bulky and relatively cumbersome to operate,thereby limiting the practical application of such instruments.

For certain applications, the broad band data provided by aspectrophotometer is unnecessary. For such applications, devices havebeen produced or proposed that quantify color in terms of a numericalvalue or relatively small set of values representative of the color ofthe object.

It is known that the color of an object can be represented by threevalues. For example, the color of an object can be represented by red,green and blue values, an intensity value and color difference values,by a CIE value, or by what are known as “tristimulus values” or numerousother orthogonal combinations. For most tristimulus systems, the threevalues are orthogonal; i.e., any combination of two elements in the setcannot be included in the third element.

One such method of quantifying the color of an object is to illuminatean object with broad band “white” light and measure the intensity of thereflected light after it has been passed through narrow band filters.Typically three filters (such as red, green and blue) are used toprovide tristimulus light values representative of the color of thesurface. Yet another method is to illuminate an object with threemonochromatic light sources or narrow band light sources (such as red,green and blue) one at a time and then measure the intensity of thereflected light with a single light sensor. The three measurements arethen converted to a tristimulus value representative of the color of thesurface. Such color measurement techniques can be utilized to produceequivalent tristimulus values representative of the color of thesurface. Generally, it does not matter if a “white” light source is usedwith a plurality of color sensors (or a continuum in the case of aspectrophotometer), or if a plurality of colored light sources areutilized with a single light sensor.

There are, however, difficulties with the conventional techniques. Whenlight is incident upon a surface and reflected to a light receiver, theheight of the light sensor and the angle of the sensor relative to thesurface and to the light source also affect the intensity of thereceived light. Since the color determination is being made by measuringand quantifying the intensity of the received light for differentcolors, it is important that the height and angular dependency of thelight receiver be eliminated or accounted for in some manner.

One method for eliminating the height and angular dependency of thelight source and receiver is to provide a fixed mounting arrangementwhere the light source and receiver are stationary and the object isalways positioned and measured at a preset height and angle. The fixedmounting arrangement greatly limits the applicability of such a method.Another method is to add mounting feet to the light source and receiverprobe and to touch the object with the probe to maintain a constantheight and angle. The feet in such an apparatus must be wide enoughapart to insure that a constant angle (usually perpendicular) ismaintained relative to the object. Such an apparatus tends to be verydifficult to utilize on small objects or on objects that are hard toreach, and in general does not work satisfactorily in measuring objectswith curved surfaces. Such devices are particularly difficult toimplement in the field of dentistry.

The use of color measuring devices in the field of dentistry has beenproposed. In modern dentistry, the color of teeth typically arequantified by manually comparing a patient's teeth with a set of “shadeguides.” There are numerous shade guides available for dentists in orderto properly select the desired color of dental prosthesis. Such shadeguides have been utilized for decades and the color determination ismade subjectively by the dentist by holding a set of shade guides nextto a patient's teeth and attempting to find the best match.Unfortunately, however, the best match often is affected by the ambientlight color in the dental operatory and the surrounding color of thepatient's makeup or clothing and by the fatigue level of the dentist. Inaddition, such pseudo trial and error methods based on subjectivematching with existing industry shade guides for forming dentalprostheses, fillings and the like often result in unacceptable colormatching, with the result that the prosthesis needs to be remade,leading to increased costs and inconvenience to the patient, dentalprofessional and/or prosthesis manufacturer.

Similar subjective color quantification also is made in the paintindustry by comparing the color of an object with a paint referenceguide. There are numerous paint guides available in the industry and thecolor determination also often is affected by ambient light color, userfatigue and the color sensitivity of the user. Many individuals arecolor insensitive (color blind) to certain colors, further complicatingcolor determination.

While a need has been recognized in the field of dentistry, however, thelimitations of conventional color/optical measuring techniques typicallyrestrict the utility of such techniques. For example, the high cost andbulkiness of typical broad band spectrometers, and the fixed mountingarrangements or feet required to address the height and angulardependency, often limit the applicability of such conventionaltechniques.

Moreover, another limitation of such conventional methods and devicesare that the resolution of the height and angular dependency problemstypically require contact with the object being measured. In certainapplications, it may be desirable to measure and quantify the color ofan object with a small probe that does not require contact with thesurface of the object. In certain applications, for example, hygienicconsiderations make such contact undesirable. In the other applications,contact with the object can mar the surface (such as if the object iscoated in some manner) or otherwise cause undesirable effects.

In summary, there is a need for a low cost, hand-held probe of smallsize that can reliably measure and quantify the color and other opticalcharacteristics of an object without requiring physical contact with theobject, and also a need for methods based on such a device in the fieldof dentistry and other applications.

SUMMARY OF THE INVENTION

In accordance with the present invention, devices and methods areprovided for measuring the color and other optical characteristics ofobjects such as teeth, reliably and with minimal problems of height andangular dependence. A handheld probe is utilized in the presentinvention, with the handheld probe containing a number of fiber opticsin certain preferred embodiments. Light is directed from one (or more)light source(s) towards the object/tooth to be measured, which incertain preferred embodiments is a central light source fiber optic(other light sources and light source arrangements also may beutilized). Light reflected from the object is detected by a number oflight receivers. Included in the light receivers (which may be lightreceiver fiber optics) are a plurality of perimeter and/or broadband orother receivers (which may be light receiver fiber optics, etc.). Incertain preferred embodiments, a number of groups of perimeter fiberoptics are utilized in order to take measurements at a desired, andpredetermined height and angle, thereby minimizing height and angulardependency problems found in conventional methods, and to quantify otheroptical characteristics such as gloss. In certain embodiments, thepresent invention also may measure gloss, translucence and fluorescencecharacteristics of the object/tooth being measured, as well as surfacetexture and/or other optical or surface characteristics. In certainembodiments, the present invention may distinguish the surface spectralreflectance response and also a bulk spectral response.

The present invention may include constituent elements of a broad bandspectrophotometer, or, alternatively, may include constituent elementsof a tristimulus type colorimeter. The present invention may employ avariety of color measuring devices in order to measure color and otheroptical characteristics in a practical, reliable and efficient manner,and in certain preferred embodiments includes a color filter array and aplurality of color sensors. A microprocessor is included for control andcalculation purposes. A temperature sensor is included to measuretemperature in order to detect abnormal conditions and/or to compensatefor temperature effects of the filters or other components of thesystem. In addition, the present invention may include audio feedback toguide the operator in making color/optical measurements, as well as oneor more display devices for displaying control, status or otherinformation.

With the present invention, color/optical measurements of teeth or thelike may be made with a handheld probe in a practical and reliablemanner, essentially free of height and angular dependency problems,without resorting to fixtures, feet or other undesirable mechanicalarrangements for fixing the height and angle of the probe with respectto the object/tooth. In addition, the present invention includes methodsof using such color measurement data to implement processes for formingdental prostheses and the like, as well as methods for keeping suchcolor and/or other data as part of a patient record database.

Accordingly, it is an object of the present invention to addresslimitations of conventional color/optical measuring techniques.

It is another object of the present invention to provide a method anddevice useful in measuring the color or other optical characteristics ofteeth or other objects or surfaces with a hand-held probe of practicalsize that may advantageously utilize, but does not necessarily require,contact with the object or surface.

It is a further object of the present invention to provide acolor/optical measurement probe and method that does not require fixedposition mechanical mounting, feet or other mechanical impediments.

It is yet another object of the present invention to provide a probe andmethod useful for measuring color and/or other optical characteristicsthat may be utilized with a probe simply placed near the surface to bemeasured.

It is a still further object of the present invention to provide a probeand method that are capable of determining translucency characteristicsof the object being measured.

It is a still further object of the present invention to provide a probeand method that are capable of determining translucency characteristicsof the object being measured by making measurements from one side of theobject.

It is a further object of the present invention to provide a probe andmethod that are capable of determining surface texture characteristicsof the object/tooth being measured.

It is a still further object of the present invention to provide a probeand method that are capable of determining fluorescence characteristicsof the object/tooth being measured.

It is yet a further object of the present invention to provide a probeand method that are capable of determining gloss (or degree of specularreflectance) characteristics of the object/tooth being measured.

It is another object of the present invention to provide a probe andmethod that can measure the area of a small spot singularly, or thatalso can measure the color of irregular shapes by moving the probe overan area and integrating the color of the entire area.

It is a further object of the present invention to provide a method ofmeasuring the color of teeth and preparing dental prostheses, dentures,intraoral tooth-colored fillings or other materials.

It is yet another object of the present invention to provide a methodand apparatus that minimizes contamination problems, while providing areliable and expedient manner in which to measure teeth and preparedental prostheses, dentures, intraoral tooth-colored fillings or othermaterials.

It is an object of the present invention to provide methods of usingmeasured data to implement processes for forming dental prostheses andthe like, as well as methods for keeping such measurement and/or otherdata as part of a patient record database.

It also is an object of the present invention to provide probes andmethods for measuring optical characteristics with a probe that is heldsubstantially stationary with respect to the object or tooth beingmeasured.

Finally, it is an object of the present invention to provide probes andmethods for measuring optical characteristics with a probe that may havea removable tip or shield that may be removed for cleaning, disposedafter use or the like

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be more fully understood by a description ofcertain preferred embodiments in conjunction with the attached drawingsin which:

FIG. 1 is a diagram illustrating a preferred embodiment of the presentinvention;

FIG. 2 is a diagram illustrating a cross section of a probe that may beused in accordance with certain embodiments of the present invention;

FIG. 3 is a diagram illustrating an illustrative arrangement of fiberoptic receivers and sensors utilized with certain embodiments;

FIGS. 4A to 4C illustrate certain geometric considerations of fiberoptics;

FIGS. 5A and 5B illustrate the light amplitude received by fiber opticlight receivers as the receivers are moved towards and away from anobject;

FIG. 6 is a flow chart illustrating a color measuring method inaccordance with an embodiment of the present invention;

FIGS. 7A and 7B illustrate a protective cap that may be used withcertain embodiments of the present invention;

FIGS. 8A and 8B illustrate removable probe tips that may be used withcertain embodiments of the present invention;

FIG. 9 illustrates a fiber optic bundle in accordance with anotherembodiment, which may serve to further the understanding of preferredembodiments of the present invention;

FIGS. 10A, 10B, 10C and 10D illustrate and describe other fiber opticbundle configurations and principles, which may serve to further theunderstanding of preferred embodiments of the present invention;

FIG. 11 illustrates a linear optical sensor array that may be used incertain embodiments of the present invention;

FIG. 12 illustrates a matrix optical sensor array that may be used incertain embodiments of the present invention;

FIGS. 13A and 13B illustrate certain optical properties of a filterarray that may be used in certain embodiments of the present invention;

FIGS. 14A and 14B illustrate examples of received light intensities ofreceivers used in certain embodiments of the present invention;

FIG. 15 is a flow chart illustrating audio tones that may be used incertain preferred embodiments of the present invention;

FIGS. 16A and 16B are flow charts illustrating dental prosthesismanufacturing methods in accordance with certain preferred embodimentsof the present invention;

FIGS. 17A and 17B illustrate a positioning implement used in certainembodiments of the present invention;

FIG. 18 is a flow chart illustrating a patient database method inaccordance with certain embodiments of the present invention;

FIG. 19 illustrates an integrated unit in accordance with the presentinvention that includes a measuring device and other implements;

FIG. 20 illustrates an embodiment, which utilizes a plurality of ringsof light receivers that may be utilized to take measurements with theprobe held substantially stationary with respect to the object beingmeasured, which may serve to further the understanding of preferredembodiments of the present invention;

FIGS. 21 and 22 illustrate an embodiment, which utilizes a mechanicalmovement and also may be utilized to take measurements with the probeheld substantially stationary with respect to the object being measured,which may serve to further the understanding of preferred embodiments ofthe present invention;

FIGS. 23A to 23C illustrate embodiments of the present invention inwhich coherent light conduits may serve as removable probe tips;

FIGS. 24, 25 and 26 illustrate further embodiments of the presentinvention utilizing intraoral reflectometers, intraoral cameras and/orcolor calibration charts in accordance with the present invention;

FIG. 27 illustrates an embodiment of the present invention in which aninteroral camera and/or other instruments in accordance with the presentinvention may be adapted for use with a dental chair;

FIGS. 28A and 28B illustrate cross sections of probes that may be usedin accordance with preferred embodiments of the present invention;

FIGS. 29 and 30A and 30B illustrate certain geometric and otherproperties of fiber optics for purposes of understanding certainpreferred embodiments;

FIGS. 31A and 31B illustrate probes for measuring “specular-excluded”type spectrums in accordance with the present invention;

FIGS. 32, 33 and 34 illustrate embodiments in which intra oral camerasand reflectometer type instruments in accordance with the presentinvention are integrated;

FIGS. 35 and 36 illustrate certain handheld embodiments of the presentinvention; and

FIGS. 37A and 37B illustrate a tooth dental object in cross section,illustrating how embodiments of the present invention may be used toassess subsurface characteristics of various types of objects

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described in greater detail with referenceto certain preferred embodiments and certain other embodiments, whichmay serve to further the understanding of preferred embodiments of thepresent invention. At various places herein, reference is made to an“object,” “material,” “surface,” etc., for example. It should beunderstood that an exemplary use of the present invention is in thefield of dentistry, and thus the object typically should be understoodto include teeth, dentures or other prosthesis or restorations,dental-type cements or the like or other dental objects, although fordiscussion purposes in certain instances reference is only made to the“object.” As described elsewhere herein, various refinements andsubstitutions of the various embodiments are possible based on theprinciples and teachings herein.

With reference to FIG. 1, an exemplary preferred embodiment of acolor/optical characteristic measuring system and method in accordancewith the present invention will be described. It should be noted that,at various places herein, such a color measuring system is sometimesreferred to as an intraoral reflectometer, etc.

Probe tip 1 encloses a plurality of fiber optics, each of which mayconstitute one or more fiber optic fibers. In a preferred embodiment,the fiber optics contained within probe tip 1 includes a single lightsource fiber optic and a number of groups of light receiver fiberoptics. The use of such fiber optics to measure the color or otheroptical characteristics of an object will be described later herein.Probe tip 1 is attached to probe body 2, on which is fixed switch 17.Switch 17 communicates with microprocessor 10 through wire 18 andprovides, for example, a mechanism by which an operator may activate thedevice in order to make a color/optical measurement. Fiber optics withinprobe tip 1 terminate at the forward end thereof (i.e., the end awayfrom probe body 2). The forward end of probe tip 1 is directed towardsthe surface of the object to be measured as described more fully below.The fiber optics within probe tip 1 optically extend through probe body2 and through fiber optic cable 3 to light sensors 8, which are coupledto microprocessor 10.

It should be noted that microprocessor 10 includes conventionalassociated components, such as memory (programmable memory, such asPROM, EPROM or EEPROM; working memory such as DRAMs or SRAMs; and/orother types of memory such as non-volatile memory, such as FLASH),peripheral circuits, clocks and power supplies, although for claritysuch components are not explicitly shown. Other types of computingdevices (such as other microprocessor systems, programmable logic arraysor the like) are used in other embodiments of the present invention.

In the embodiment of FIG. 1, the fiber optics from fiber optic cable 3end at splicing connector 4. From splicing connector 4, each or some ofthe receiver fiber optics used in this embodiment is/are spliced into anumber of smaller fiber optics (generally denoted as fibers 7), which inthis embodiment are fibers of equal diameter, but which in otherpreferred embodiments may be of unequal diameter and/or numeric aperture(NA) (including, for example, larger or smaller “height/angle” orperimeter fibers, as more fully described herein). One of the fibers ofeach group of fibers may pass to light sensors 8 through a neutraldensity filter (as more fully described with reference to FIG. 3), andcollectively such neutrally filtered fibers may be utilized for purposesof height/angle determination, translucency determination and glossdetermination (and also may be utilized to measure other surfacecharacteristics, as more fully described herein). Remaining fibers ofeach group of fibers may pass to light sensors 8 through color filtersand may be used to make color/optical measurements. In still otherembodiments, splicing connector 4 is not used, and fiber bundles of, forexample, five or more fibers each extend from light sensors 8 to theforward end of probe tip 1. In certain embodiments, unused fibers orother materials may be included as part of a bundle of fibers forpurposes of, for example, easing the manufacturing process for the fiberbundle. What should be noted is that, for purposes of the presentinvention, a plurality of light receiver fiber optics or elements (suchas fibers 7) are presented to light sensors 8, with the light from thelight receiver fiber optics/elements representing light reflected fromobject 20. While the various embodiments described herein presenttradeoffs and benefits that may not have been apparent prior to thepresent invention (and thus may be independently novel), what isimportant for the present discussion is that light from fiberoptics/elements at the forward end of probe tip 1 is presented tosensors 8 for color/optical measurements and angle/height determination,etc. In particular, fiber optic configurations of certain preferredembodiments will be explained in more detail hereinafter.

Light source 11 in the preferred embodiment is a halogen light source(of, for example, 5-100 watts, with the particular wattage chosen forthe particular application), which may be under the control ofmicroprocessor 10. The light from light source 11 reflects from coldmirror 6 and into source fiber optic 5. Source fiber optic 5 passesthrough to the forward end of probe tip 1 and provides the lightstimulus used for purposes of making the measurements described herein.Cold mirror 6 reflects visible light and passes infra-red light, and isused to reduce the amount of infra-red light produced by light source 11before the light is introduced into source fiber optic 5. Such infra-redlight reduction of the light from a halogen source such as light source11 can help prevent saturation of the receiving light sensors, which canreduce overall system sensitivity. Fiber 15 receives light directly fromlight source 11 and passes through to light sensors 8 (which may bethrough a neutral density filter). Microprocessor 10 monitors the lightoutput of light source 11 through fiber 15, and thus may monitor and, ifnecessary compensate for, drift of the output of light source 11. Incertain embodiments, microprocessor 10 also may sound an alarm (such asthrough speaker 16) or otherwise provide some indication if abnormal orother undesired performance of light source 11 is detected.

The data output from light sensors 8 pass to microprocessor 10.Microprocessor 10 processes the data from light sensors 8 to produce ameasurement of color and/or other characteristics. Microprocessor 10also is coupled to key pad switches 12, which serve as an input device.Through key pad switches 12, the operator may input control informationor commands, or information relating to the object being measured or thelike. In general, key pad switches 12, or other suitable data inputdevices (such as push button, toggle, membrane or other switches or thelike), serve as a mechanism to input desired information tomicroprocessor 10.

Microprocessor 10 also communicates with UART 13, which enablesmicroprocessor 10 to be coupled to an external device such as computer13A. In such embodiments, data provided by microprocessor 10 may beprocessed as desired for the particular application, such as foraveraging, format conversion or for various display or print options,etc. In the preferred embodiment, UART 13 is configured so as to providewhat is known as a RS232 interface, such as is commonly found inpersonal computers.

Microprocessor 10 also communicates with LCD 14 for purposes ofdisplaying status, control or other information as desired for theparticular application. For example, color bars, charts or other graphicrepresentations of the color or other collected data and/or the measuredobject or tooth may be displayed. In other embodiments, other displaydevices are used, such as CRTs, matrix-type LEDs, lights or othermechanisms for producing a visible indicia of system status or the like.Upon system initialization, for example, LCD 14 may provide anindication that the system is stable, ready and available for takingcolor measurements.

Also coupled to microprocessor 10 is speaker 16. Speaker 16, in apreferred embodiment as discussed more fully below, serves to provideaudio feedback to the operator, which may serve to guide the operator inthe use of the device. Speaker 16 also may serve to provide status orother information alerting the operator of the condition of the system,including an audio tone, beeps or other audible indication (i.e., voice)that the system is initialized and available for taking measurements.Speaker 16 also may present audio information indicative of the measureddata, shade guide or reference values corresponding to the measureddata, or an indication of the status of the color/optical measurements.

Microprocessor 10 also receives an input from temperature sensor 9.Given that many types of filters (and perhaps light sources or othercomponents) may operate reliably only in a given temperature range,temperature sensor 9 serves to provide temperature information tomicroprocessor 10. In particular, color filters, such as may be includedin light sensors 8, may be sensitive to temperature, and may operatereliably only over a certain temperature range. In certain embodiments,if the temperature is within a usable range, microprocessor 10 maycompensate for temperature variations of the color filters. In suchembodiments, the color filters are characterized as to filteringcharacteristics as a function of temperature, either by data provided bythe filter manufacturer, or through measurement as a function oftemperature. Such filter temperature compensation data may be stored inthe form of a look-up table in memory, or may be stored as a set ofpolynomial coefficients from which the temperature characteristics ofthe filters may be computed by microprocessor 10.

In general, under control of microprocessor 10, which may be in responseto operator activation (through, for example, key pad switches 12 orswitch 17), light is directed from light source 11, and reflected fromcold mirror 6 through source fiber optic 5 (and through fiber opticcable 3, probe body 2 and probe tip 1) or through some other suitablelight source element and is directed onto object 20. Light reflectedfrom object 20 passes through the receiver fiber optics/elements inprobe tip 1 to light sensors 8 (through probe body 2, fiber optic cable3 and fibers 7). Based on the information produced by light sensors 8,microprocessor 10 produces a color/optical measurement result or otherinformation to the operator. Color measurement or other data produced bymicroprocessor 10 may be displayed on display 14, passed through UART 13to computer 13A, or used to generate audio information that is presentedto speaker 16. Other operational aspects of the preferred embodimentillustrated in FIG. 1 will be explained hereinafter.

With reference to FIG. 2, an embodiment of a fiber optic arrangementpresented at the forward end of probe tip 1 will now be described, whichmay serve to further the understanding of preferred embodiments of thepresent invention. As illustrated in FIG. 2, this embodiment utilizes asingle central light source fiber optic, denoted as light source fiberoptic S, and a plurality of perimeter light receiver fiber optics,denoted as light receivers R1, R2 and R3. As is illustrated, thisembodiment utilizes three perimeter fiber optics, although in otherembodiments two, four or some other number of receiver fiber optics areutilized. As more fully described herein, the perimeter light receiverfiber optics serve not only to provide reflected light for purposes ofmaking the color/optical measurement, but such perimeter fibers alsoserve to provide information regarding the angle and height of probe tip1 with respect to the surface of the object that is being measured, andalso may provide information regarding the surface characteristics ofthe object that is being measured.

In the illustrated embodiment, receiver fiber optics R1 to R3 arepositioned symmetrically around source fiber optic S, with a spacing ofabout 120 degrees from each other. It should be noted that spacing t isprovided between receiver fiber optics R1 to R3 and source fiber opticS. While the precise angular placement of the receiver fiber opticsaround the perimeter of the fiber bundle in general is not critical, ithas been determined that three receiver fiber optics positioned 120degrees apart generally may give acceptable results. As discussed above,in certain embodiments light receiver fiber optics R1 to R3 eachconstitute a single fiber, which is divided at splicing connector 4(refer again to FIG. 1), or, in alternate embodiments, light receiverfiber optics R1 to R3 each constitute a bundle of fibers, numbering, forexample, at least five fibers per bundle. It has been determined that,with available fibers of uniform size, a bundle of, for example, sevenfibers may be readily produced (although as will be apparent to one ofskill in the art, the precise number of fibers may be determined in viewof the desired number of receiver fiber optics, manufacturingconsiderations, etc.). The use of light receiver fiber optics R1 to R3to produce color/optical measurements is further described elsewhereherein, although it may be noted here that receiver fiber optics R1 toR3 may serve to detect whether, for example, the angle of probe tip 1with respect to the surface of the object being measured is at 90degrees, or if the surface of the object being measured contains surfacetexture and/or spectral irregularities. In the case where probe tip 1 isperpendicular to the surface of the object being measured and thesurface of the object being measured is a diffuse reflector (i.e., amatte-type reflector, as compared to a glossy or spectral or shiny-typereflector which may have “hot spots”), then the light intensity inputinto the perimeter fibers should be approximately equal. It also shouldbe noted that spacing t serves to adjust the optimal height at whichcolor/optical measurements should be made (as more fully describedbelow). Preferred embodiments, as described hereinafter, may enable thequantification of the gloss or degree of spectral reflection of theobject being measured.

In one particular aspect useful with embodiments of the presentinvention, area between the fiber optics on probe tip 1 may be wholly orpartially filled with a non-reflective material and/or surface (whichmay be a black mat, contoured or other non-reflective surface). Havingsuch exposed area of probe tip 1 non-reflective helps to reduceundesired reflections, thereby helping to increase the accuracy andreliability.

With reference to FIG. 3, a partial arrangement of light receiver fiberoptics and sensors that may be used in a preferred embodiment of thepresent invention will now be described. Fibers 7 represent lightreceiving fiber optics, which transmit light reflected from the objectbeing measured to light sensors 8. In an exemplary embodiment, sixteensensors (two sets of eight) are utilized, although for ease ofdiscussion only 8 are illustrated in FIG. 3 (in this preferredembodiment, the circuitry of FIG. 3 is duplicated, for example, in orderto result in sixteen sensors). In other embodiments, other numbers ofsensors are utilized in accordance with the present invention.

Light from fibers 7 is presented to sensors 8, which in a preferredembodiment pass through filters 22 to sensing elements 24. In thispreferred embodiment, sensing elements 24 include light-to-frequencyconverters, manufactured by Texas Instruments and sold under the partnumber TSL230. Such converters constitute, in general, photo diodearrays that integrate the light received from fibers 7 and output an ACsignal with a frequency proportional to the intensity (not frequency) ofthe incident light. Without being bound by theory, the basic principleof such devices is that, as the intensity increases, the integratoroutput voltage rises more quickly, and the shorter the integrator risetime, the greater the output frequency. The outputs of the TSL230sensors are TL compatible digital signals, which may be coupled tovarious digital logic devices.

The outputs of sensing elements 24 are, in this embodiment, asynchronoussignals of frequencies depending upon the light intensity presented tothe particular sensing elements, which are presented to processor 26. Ina preferred embodiment, processor 26 is a Microchip PIC16C55 or PIC16C57 microprocessor, which as described more fully herein implements analgorithm to measure the frequencies of the signals output by sensingelements 24. In other embodiments, a more integratedmicroprocessor/microcontroller, such as Hitachi's SH RISCmicrocontrollers, is utilized to provide further system integration orthe like.

As previously described, processor 26 measures the frequencies of thesignals output from sensing elements 24. In a preferred embodiment,processor 26 implements a software timing loop, and at periodicintervals processor 26 reads the states of the outputs of sensingelements 24. An internal counter is incremented each pass through thesoftware timing loop. The accuracy of the timing loop generally isdetermined by the crystal oscillator time base (not shown in FIG. 3)coupled to processor 26 (such oscillators typically are quite stable).After reading the outputs of sensing elements 24, processor 26 performsan exclusive OR (“XOR”) operation with the last data read (in apreferred embodiment such data is read in byte length). If any bit haschanged, the XOR operation will produce a 1, and, if no bits havechanged, the XOR operation will produce a 0. If the result is non-zero,the input byte is saved along with the value of the internal counter(that is incremented each pass through the software timing loop). If theresult is zero, the systems waits (e.g., executes no operationinstructions) the same amount of time as if the data had to be saved,and the looping operation continues. The process continues until alleight inputs have changed at least twice, which enables measurement of afull ½ period of each input. Upon conclusion of the looping process,processor 26 analyzes the stored input bytes and internal counterstates. There should be 2 to 16 saved inputs (for the 8 total sensors ofFIG. 3) and counter states (if two or more inputs change at the sametime, they are saved simultaneously). As will be understood by one ofskill in the art, the stored values of the internal counter containsinformation determinative of the period of the signals received fromsensing elements 24. By proper subtraction of internal counter values attimes when an input bit has changed, the period may be calculated. Suchperiods calculated for each of the outputs of sensing elements isprovided by processor 26 to microprocessor 10 (see, e.g., FIG. 1). Fromsuch calculated periods, a measure of the received light intensities maybe calculated. In alternate embodiments, the frequency of the outputs ofthe TSL230 sensors is measured directly by a similar software loop asthe one described above. The outputs are monitored by the RISC processorin a software timing loop and are XORed with the previous input asdescribed above. If a transition occurs for a particular TSL230 input, acounter register for the particular TSL230 input is incremented. Thesoftware loop is executed for a pre-determined period of time and thefrequency of the input is calculated by dividing the number oftransitions by the pre-determined time and scaling the result. It willalso be apparent to one skilled in the art that more sophisticatedmeasurement schemes can also be implemented whereby both the frequencyand period are simultaneously measured by high speed RISC processorssuch as those of the Hitachi SH family.

It should be noted that the sensing circuitry and methodologyillustrated in FIG. 3 have been determined to provide a practical andexpedient manner in which to measure the light intensities received bysensing elements 24. In other embodiments, other circuits andmethodologies are employed (such other exemplary sensing schemes aredescribed elsewhere herein).

As discussed above with reference to FIG. 1, one or more of fibers 7measures light source 11, which may be through a neutral density filter,which serves to reduce the intensity of the received light in order tomaintain the intensity roughly in the range of the other received lightintensities. A number of fibers 7 also are from perimeter receiver fiberoptics R1 to R3 (see, e.g., FIG. 2) and also may pass through neutraldensity filters. Such receiving fibers 7 serve to provide data fromwhich angle/height information and/or surface characteristics may bedetermined.

The remaining twelve fibers (of the illustrated embodiment's total of 16fibers) of fibers 7 pass through color filters and are used to producethe color measurement. In an embodiment, the color filters are KodakSharp Cutting Wratten Gelatin Filters, which pass light with wavelengthsgreater than the cut-off value of the filter (i.e., redish values), andabsorb light with wavelengths less than the cut-off value of the filter(i.e., bluish values). “Sharp Cutting” filters are available in a widevariety of cut-off frequencies/wavelengths, and the cut-off valuesgenerally may be selected by proper selection of the desired cut-offfilter. In an embodiment, the filter cut-off values are chosen to coverthe entire visible spectrum and, in general, to have band spacings ofapproximately the visible band range (or other desired range) divided bythe number of receivers/filters. As an example, 700 nanometers minus 400nanometers, divided by 11 bands (produced by twelve colorreceivers/sensors), is roughly 30 nanometer band spacing.

With an array of cut-off filters as described above, and without beingbound by theory or the specific embodiments described herein, thereceived optical spectrum may be measured/calculated by subtracting thelight intensities of “adjacent” color receivers. For example, band 1(400 nm to 430 nm)=(intensity of receiver 12) minus (intensity ofreceiver 11), and so on for the remaining bands. Such an array ofcut-off filters, and the intensity values that may result from filteringwith such an array, are more fully described in connection with FIGS.13A to 14B.

It should be noted here that in alternate embodiments other color filterarrangements are utilized. For example, “notch” or bandpass filters maybe utilized, such as may be developed using Schott glass-type filters(whether constructed from separate longpass/shortpass filters orotherwise) or notch interference filters such as those manufactured byCorion, etc.

In a preferred embodiment of the present invention, the specificcharacteristics of the light source, filters, sensors and fiber optics,etc., are normalized/calibrated by directing the probe towards, andmeasuring, a known color standard. Such normalization/calibration may beperformed by placing the probe in a suitable fixture, with the probedirected from a predetermined position (i.e., height and angle) from theknown color standard. Such measured normalization/calibration data maybe stored, for example, in a look-up table, and used by microprocessor10 to normalize or correct measured color or other data. Such proceduresmay be conducted at start-up, at regular periodic intervals, or byoperator command, etc. In particular embodiments, a large number ofmeasurements may be taken on materials of particular characteristics andprocessed and/or statistically analyzed or the like, with datarepresenting or derived from such measurements stored in memory (such asa look-up table or polynomial or other coefficients, etc.). Thereafter,based upon measurements of an object taken in accordance with thepresent invention, comparisons may be made with the stored data andassessments of the measured object made or predicted. In oneillustrative example, an assessment or prediction may be made of whetherthe object is wet or dry (having water or other liquid on its surface,wet paint, etc.) based on measurements in accordance with the presentinvention. In yet another illustrative example, an assessment orprediction of the characteristics of an underlying material, such as thepulpal tissue within a tooth may be made. Such capabilities may befurther enhanced by comparisons with measurements taken of the object atan earlier time, such as data taken of the tooth or other object at oneor more earlier points in time. Such comparisons based on suchhistorical data and/or stored data may allow highly useful assessmentsor predictions of the current or projected condition or status of thetooth, tissue or other object, etc. Many other industrial uses of suchsurface and subsurface assessment/prediction capabilities are possible.

What should be noted from the above description is that the receivingand sensing fiber optics and circuitry illustrated in FIG. 3 provide apractical and expedient way to determine the color and other optical orother characteristics by measuring the intensity of the light reflectedfrom the surface of the object being measured.

It also should be noted that such a system measures the spectral band ofthe reflected light from the object, and once measured such spectraldata may be utilized in a variety of ways. For example, such spectraldata may be displayed directly as intensity-wavelength band values. Inaddition, tristimulus type values may be readily computed (through, forexample, conventional matrix math), as may any other desired colorvalues. In one particular embodiment useful in dental applications (suchas for dental prostheses), the color data is output in the form of aclosest match or matches of dental shade guide value(s). In a preferredembodiment, various existing shade guides (such as the shade guidesproduced by Vita Zahnfabrik) are characterized and stored in a look-uptable, or in the graphics art industry Pantone color references, and thecolor measurement data are used to select the closest shade guide valueor values, which may be accompanied by a confidence level or othersuitable factor indicating the degree of closeness of the match ormatches, including, for example, what are known as ΔE values or rangesof ΔE values, or criteria based on standard deviations, such as standarddeviation minimization. In still other embodiments, the colormeasurement data are used (such as with look-up tables) to selectmaterials for the composition of paint or ceramics such as forprosthetic teeth. There are many other uses of such spectral datameasured in accordance with the present invention.

It is known that certain objects such as human teeth may fluoresce, andsuch optical characteristics also may be measured in accordance with thepresent invention. A light source with an ultraviolet component may beused to produce more accurate color/optical data with respect to suchobjects. Such data may be utilized to adjust the amounts and orproportions or types of dental fluorescing materials in dentalrestorations or prosthesis. In certain embodiments, a tungsten/halogensource (such as used in a preferred embodiment) may be combined with aUV light source (such as a mercury vapor, xenon or other fluorescentlight source, etc.) to produce a light output capable of causing theobject to fluoresce. Alternately, a separate UV light source, combinedwith a visible-light-blocking filter, may be used to illuminate theobject. Such a UV light source may be combined with light from a red LED(for example) in order to provide a visual indication of when the UVlight is on and also to serve as an aid for the directional positioningof the probe operating with such a light source. A second measurementmay be taken using the UV light source in a manner analogous to thatdescribed earlier, with the band of the red LED or other supplementallight source being ignored. The second measurement may thus be used toproduce an indication of the fluorescence of the tooth or other objectbeing measured. With such a UV light source, a silica fiber optic (orother suitable material) typically would be required to transmit thelight to the object (standard fiber optic materials such as glass andplastic in general do not propagate UV light in a desired manner, etc.).

As described earlier, in certain preferred embodiments the presentinvention utilizes a plurality of perimeter receiver fiber optics spacedapart from and around a central source fiber optic to measure color anddetermine information regarding the height and angle of the probe withrespect to the surface of the object being measured, which may includeother surface characteristic information, etc. Without being bound bytheory, certain principles underlying certain aspects of the presentinvention will now be described with reference to FIGS. 4A to 4C.

FIG. 4A illustrates a typical step index fiber optic consisting of acore and a cladding. For this discussion, it is assumed that the corehas an index of refraction of n₀ and the cladding has an index ofrefraction of n₁. Although the following discussion is directed to “stepindex” fibers, it will be appreciated by those of skill in the art thatsuch discussion generally is applicable for gradient index fibers aswell.

In order to propagate light without loss, the light must be incidentwithin the core of the fiber optic at an angle greater than the criticalangle, which may be represented as Sin⁻¹ {n₁/n₀}, where n₀ is the indexof refraction of the core and n₁ is the index of refraction of thecladding. Thus, all light must enter the fiber at an acceptance angleequal to or less than phi, with phi=2×Sin⁻¹{(n₀ ²−n₁ ²)}, or it will notbe propagated in a desired manner.

For light entering a fiber optic, it must enter within the acceptanceangle phi. Similarly, when the light exits a fiber optic, it will exitthe fiber optic within a cone of angle phi as illustrated in FIG. 4A.The value (n₀ ²−n₁ ²) is referred to as the aperture of the fiber optic.For example, a typical fiber optic may have an aperture of 0.5, and anacceptance angle of 60°.

Consider using a fiber optic as a light source. One end is illuminatedby a light source (such as light source 11 of FIG. 1), and the other isheld near a surface. The fiber optic will emit a cone of light asillustrated in FIG. 4A. If the fiber optic is held perpendicular to asurface it will create a circular light pattern on the surface. As thefiber optic is raised, the radius r of the circle will increase. As thefiber optic is lowered, the radius of the light pattern will decrease.Thus, the intensity of the light (light energy per unit area) in theilluminated circular area will increase as the fiber optic is loweredand will decrease as the fiber optic is raised.

The same principle generally is true for a fiber optic being utilized asa receiver. Consider mounting a light sensor on one end of a fiber opticand holding the other end near an illuminated surface. The fiber opticcan only propagate light without loss when the light entering the fiberoptic is incident on the end of the fiber optic near the surface if thelight enters the fiber optic within its acceptance angle phi. A fiberoptic utilized as a light receiver near a surface will only accept andpropagate light from the circular area of radius r on the surface. Asthe fiber optic is raised from the surface, the area increases. As thefiber optic is lowered to the surface, the area decreases.

Consider two fiber optics parallel to each other as illustrated in FIG.4B. For simplicity of discussion, the two fiber optics illustrated areidentical in size and aperture. The following discussion, however,generally would be applicable for fiber optics that differ in size andaperture. One fiber optic is a source fiber optic, the other fiber opticis a receiver fiber optic. As the two fiber optics are heldperpendicular to a surface, the source fiber optic emits a cone of lightthat illuminates a circular area of radius r. The receiver fiber opticcan only accept light that is within its acceptance angle phi, or onlylight that is received within a cone of angle phi. If the only lightavailable is that emitted by the source fiber optic, then the only lightthat can be accepted by the receiver fiber optic is the light thatstrikes the surface at the intersection of the two circles asillustrated in FIG. 4C. As the two fiber optics are lifted from thesurface, the proportion of the intersection of the two circular areasrelative to the circular area of the source fiber optic increases. Asthey near the surface, the proportion of the intersection of the twocircular areas to the circular area of the source fiber optic decreases.If the fiber optics are held too close to the surface (i.e., at or belowa “critical height” h_(c)), the circular areas will no longer intersectand no light emitted from the source fiber optic will be received by thereceiver fiber optic.

As discussed earlier, the intensity of the light in the circular areailluminated by the source fiber increases as the fiber is lowered to thesurface. The intersection of the two cones, however, decreases as thefiber optic pair is lowered. Thus, as the fiber optic pair is lowered toa surface, the total intensity of light received by the receiver fiberoptic increases to a maximal value, and then decreases sharply as thefiber optic pair is lowered still further to the surface. Eventually,the intensity will decrease essentially to zero at or below the criticalheight h_(c) (assuming the object being measured is not translucent, asdescribed more fully herein), and will remain essentially zero until thefiber optic pair is in contact with the surface. Thus, as asource-receiver pair of fiber optics as described above are positionednear a surface and as their height is varied, the intensity of lightreceived by the receiver fiber optic reaches a maximal value at apeaking or “peaking height” h_(p).

Again without being bound by theory, an interesting property of thepeaking height h_(p) has been observed. The peaking height h_(p) is afunction primarily of the geometry of fixed parameters, such as fiberapertures, fiber diameters and fiber spacing. Since the receiver fiberoptic in the illustrated arrangement is only detecting a maximum valueand not attempting to quantify the value, its maximum in general isindependent of the surface color. It is only necessary that the surfacereflect sufficient light from the intersecting area of the source andreceiver fiber optics to be within the detection range of the receiverfiber optic light sensor. Thus, in general red or green or blue or anycolor surface will all exhibit a maximum at the same peaking heighth_(p).

Although the above discussion has focused on two fiber opticsperpendicular to a surface, similar analysis is applicable for fiberoptic pairs at other angles. When a fiber optic is not perpendicular toa surface, it generally illuminates an elliptical area. Similarly, theacceptance area of a receiver fiber optic generally becomes elliptical.As the fiber optic pair is moved closer to the surface, the receiverfiber optic also will detect a maximal value at a peaking heightindependent of the surface color or characteristics. The maximalintensity value measured when the fiber optic pair is not perpendicularto the surface, however, will be less than the maximal intensity valuemeasured when the fiber optic pair is perpendicular to the surface.

Referring now to FIGS. 5A and 5B, the intensity of light received as afiber optic source-receiver pair is moved to and from a surface will nowbe described. FIG. 5A illustrates the intensity of the received light asa function of time. Corresponding FIG. 5B illustrates the height of thefiber optic pair from the surface of the object being measured. FIGS. 5Aand 5B illustrate (for ease of discussion) a relatively uniform rate ofmotion of the fiber optic pair to and from the surface of the objectbeing measured (although similar illustrations/analysis would beapplicable for non-uniform rates as well).

FIG. 5A illustrates the intensity of received light as the fiber opticpair is moved to and then from a surface. While FIG. 5A illustrates theintensity relationship for a single receiver fiber optic, similarintensity relationships would be expected to be observed for otherreceiver fiber optics, such as, for example, the multiple receiver fiberoptics of FIGS. 1 and 2. In general with the preferred embodimentdescribed above, all fifteen fiber optic receivers (of fibers 7) willexhibit curves similar to that illustrated in FIG. 5A.

FIG. 5A illustrates five regions. In region 1, the probe is movedtowards the surface of the object being measured, which causes thereceived light intensity to increase. In region 2, the probe is movedpast the peaking height, and the received light intensity peaks and thenfalls off sharply. In region 3, the probe essentially is in contact withthe surface of the object being measured. As illustrated, the receivedintensity in region 3 will vary depending upon the translucence of theobject being measured. If the object is opaque, the received lightintensity will be very low, or almost zero (perhaps out of range of thesensing circuitry). If the object is translucent, however, the lightintensity will be quite high, but in general should be less than thepeak value. In region 4, the probe is lifted and the light intensityrises sharply to a maximum value. In region 5, the probe is liftedfurther away from the object, and the light intensity decreases again.

As illustrated, two peak intensity values (discussed as P1 and P2 below)should be detected as the fiber optic pair moves to and from the objectat the peaking height h_(p). If peaks P1 and P2 produced by a receiverfiber optic are the same value, this generally is an indication that theprobe has been moved to and from the surface of the object to bemeasured in a consistent manner. If peaks P1 and P2 are of differentvalues, then these may be an indication that the probe was not moved toand from the surface of the object in a desired manner, or that thesurface is curved or textured, as described more fully herein. In such acase, the data may be considered suspect and rejected. In addition,peaks P1 and P2 for each of the perimeter fiber optics (see, e.g., FIG.2) should occur at the same height (assuming the geometric attributes ofthe perimeter fiber optics, such as aperture, diameter and spacing fromthe source fiber optic, etc.). Thus, the perimeter fiber optics of aprobe moved in a consistent, perpendicular manner to and from thesurface of the object being measured should have peaks P1 and P2 thatoccur at the same height. Monitoring receiver fibers from the perimeterreceiver fiber optics and looking for simultaneous (or nearsimultaneous, e.g., within a predetermined range) peaks P1 and P2provides a mechanism for determining if the probe is held at a desiredperpendicular angle with respect to the object being measured.

In addition, the relative intensity level in region 3 serves as anindication of the level of translucency of the object being measured.Again, such principles generally are applicable to the totality ofreceiver fiber optics in the probe (see, e.g., fibers 7 of FIGS. 1 and3). Based on such principles, measurement techniques that may beapplicable with respect to embodiments disclosed herein will now bedescribed.

FIG. 6 is a flow chart illustrating a general measuring technique thatmay be used in accordance with certain embodiments of the presentinvention. Step 49 indicates the start or beginning of a color/opticalmeasurement. During step 49, any equipment initialization, diagnostic orsetup procedures may be performed. Audio or visual information or otherindicia may be given to the operator to inform the operator that thesystem is available and ready to take a measurement. Initiation of thecolor/optical measurement commences by the operator moving the probetowards the object to be measured, and may be accompanied by, forexample, activation of switch 17 (see FIG. 1).

In step 50, the system on a continuing basis monitors the intensitylevels for the receiver fiber optics (see, e.g., fibers 7 of FIG. 1). Ifthe intensity is rising, step 50 is repeated until a peak is detected.If a peak is detected, the process proceeds to step 52. In step 52,measured peak intensity P1, and the time at which such peak occurred,are stored in memory (such as in memory included as a part ofmicroprocessor 10), and the process proceeds to step 54. In step 54, thesystem continues to monitor the intensity levels of the receiver fiberoptics. If the intensity is falling, step 54 is repeated. If a “valley”or plateau is detected (i.e., the intensity is no longer falling, whichgenerally indicates contact or near contact with the object), then theprocess proceeds to step 56. In step 56, the measured surface intensity(IS) is stored in memory, and the process proceeds to step 58. In step58, the system continues to monitor the intensity levels of the receiverfibers. If the intensity is rising, step 58 is repeated until a peak isdetected. If a peak is detected, the process proceeds to step 60. Instep 60, measured peak intensity P2, and the time at which such peakoccurred, are stored in memory, and the process proceeds to step 62. Instep 62, the system continues to monitor the intensity levels of thereceiver fiber optics. Once the received intensity levels begin to fallfrom peak P2, the system perceives that region 5 has been entered (see,e.g., FIG. 5A), and the process proceeds to step 64.

In step 64, the system, under control of microprocessor 10, may analyzethe collected data taken by the sensing circuitry for the variousreceiver fiber optics. In step 64, peaks P1 and P2 of one or more of thevarious fiber optics may be compared. If any of peaks P1 and P2 for anyof the various receiver fiber optics have unequal peak values, then thedata may be rejected, and the entire color measuring process repeated.Again, unequal values of peaks P1 and P2 may be indicative, for example,that the probe was moved in a non-perpendicular or otherwise unstablemanner (i.e., angular or lateral movement), and, for example, peak P1may be representative of a first point on the object, while peak P2 maybe representative of a second point on the object. As the data issuspect, in a preferred embodiment of the present invention, data takenin such circumstances are rejected in step 64.

If the data are not rejected in step 64, the process proceeds to step66. In step 66, the system analyzes the data taken from theneutral-density-filtered receivers from each of the perimeter fiberoptics (e.g., R1 to R3 of FIG. 2). If the peaks of the perimeter fiberoptics did not occur at or about the same point in time, this may beindicative, for example, that the probe was not held perpendicular tothe surface of the object being measured. As non-perpendicular alignmentof the probe with the surface of the object being measured may causesuspect results, in a preferred embodiment of the present invention,data taken in such circumstances are rejected in step 66. In onepreferred embodiment, detection of simultaneous or near simultaneouspeaking (peaking within a predetermined range of time) serves as anacceptance criterion for the data, as perpendicular alignment generallyis indicated by simultaneous or near simultaneous peaking of theperimeter fiber optics. In other embodiments, step 66 includes ananalysis of peak values P1 and P2 of the perimeter fiber optics. In suchembodiments, the system seeks to determine if the peak values of theperimeter fiber optics (perhaps normalized with any initial calibrationdata) are equal within a defined range. If the peak values of theperimeter fiber optics are within the defined range, the data may beaccepted, and if not, the data may be rejected. In still otherembodiments, a combination of simultaneous peaking and equal valuedetection are used as acceptance/rejection criteria for the data, and/orthe operator may have the ability (such as through key pad switches 12)to control one or more of the acceptance criteria ranges. With suchcapability, the sensitivity of the system may be controllably altered bythe operator depending upon the particular application and operativeenvironment, etc.

If the data are not rejected in step 66, the process proceeds to step68. In step 68, the color data may be processed in a desired manner toproduce output color/optical measurement data. For example, such datamay be normalized in some manner, or adjusted based on temperaturecompensation, or translucency data, or gloss data or surface texturedata or non-perpendicular angle data other data detected by the system.The data also may be converted to different display or other formats,depending on the intended use of the data. In addition, the dataindicative of the translucence of the object and/or glossiness of theobject also may be quantified and/or displayed in step 68. After step68, the process may proceed to starting step 49, or the process may beterminated, etc. As indicated previously, such data also may be comparedwith previously-stored data for purposes of making assessments orpredictions, etc., of a current or future condition or status.

In accordance with the process illustrated in FIG. 6, three lightintensity values (P1, P2 and IS) are stored per receiver fiber optic tomake color and translucency, etc., measurements. If stored peak valuesP1 and P2 are not equal (for some or all of the receivers), this is anindication that the probe was not held steady over one area, and thedata may be rejected (in other embodiments, the data may not berejected, although the resulting data may be used to produce an averageof the measured data). In addition, peak values P1 and P2 for the threeneutral density perimeter fiber optics should be equal or approximatelyequal; if this is not the case, then this is an indication that theprobe was not held perpendicular or a curved surface is being measured.In other embodiments, the system attempts to compensate for curvedsurfaces and/or non-perpendicular angles. In any event, if the systemcannot make a color/optical measurement, or if the data is rejectedbecause peak values P1 and P2 are unequal to an unacceptable degree orfor some other reason, then the operator is notified so that anothermeasurement or other action may be taken (such as adjust thesensitivity).

With a system constructed and operating as described above,color/optical measurements may be taken of an object, with accepted datahaving height and angular dependencies removed. Data not taken at thepeaking height, or data not taken with the probe perpendicular to thesurface of the object being measured, etc., are rejected in certainembodiments. In other embodiments, data received from the perimeterfiber optics may be used to calculate the angle of the probe withrespect to the surface of the object being measured, and in suchembodiments non-perpendicular or curved surface data may be compensatedinstead of rejected. It also should be noted that peak values P1 and P2for the neutral density perimeter fiber optics provide a measurement ofthe luminance (gray value) of the surface of the object being measured,and also may serve to quantify the color value.

The translucency of the object being measured may be quantified as aratio or percentage, such as, for example, (IS/P1)×100%. In otherembodiments, other methods of quantifying translucency data provided inaccordance with the present invention are utilized, such as some otherarithmetic function utilizing IS and P1 or P2, etc. Translucenceinformation, as would be known to those in the art, could be used toquantify and/or adjust the output color data, etc.

In another particular aspect of the present invention, data generated inaccordance with the present invention may be used to implement anautomated material mixing/generation machine and/or method. Certainobjects/materials, such as dental prostheses or fillings, are made fromporcelain or other powders/resins/materials or tissue substitutes thatmay be combined in the correct ratios or modified with additives to formthe desired color of the object/prosthesis. Certain powders oftencontain pigments that generally obey Beer's law and/or act in accordancewith Kubelka-Munk equations and/or Saunderson equations (if needed) whenmixed in a recipe. Color and other data taken from a measurement inaccordance with the present invention may be used to determine orpredict desired quantities of pigment or other materials for the recipe.Porcelain powders and other materials are available in different colors,opacities, etc. Certain objects, such as dental prostheses, may belayered to simulate the degree of translucency of the desired object(such as to simulate a human tooth). Data generated in accordance withthe present invention also may be used to determine the thickness andposition of the porcelain or other material layers to more closelyproduce the desired color, translucency, surface characteristics, etc.In addition, based on fluorescence data for the desired object, thematerial recipe may be adjusted to include a desired quantity offluorescing-type material. In yet other embodiments, surfacecharacteristics (such as texture) information (as more fully describedherein) may be used to add a texturing material to the recipe, all ofwhich may be carried out in accordance with the present invention. Inyet other embodiments, the degree of surface polish to the prosthesismay be monitored or adjusted, based on gloss data derived in accordancewith the present invention.

For more information regarding such pigment-material recipe typetechnology, reference may be made to: “The Measurement of Appearance,”Second Edition, edited by Hunter and Harold, copyright 1987; “Principlesof Color Technology,” by Billmeyer and Saltzman, copyright 1981; and“Pigment Handbook,” edited by Lewis, copyright 1988. All of theforegoing are believed to have been published by John Wiley & Sons,Inc., New York, N.Y., and all of which are hereby incorporated byreference.

In certain operative environments, such as dental applications,contamination of the probe is of concern. In certain embodiments of thepresent invention, implements to reduce such contamination are provided.

FIGS. 7A and 7B illustrate a protective cap that may be used to fit overthe end of probe tip 1. Such a protective cap consists of body 80, theend of which is covered by optical window 82, which in a preferredembodiment consists of a structure having a thin sapphire window. In apreferred embodiment, body 80 consists of stainless steel. Body 80 fitsover the end of probe tip 1 and may be held into place by, for example,indentations formed in body 80, which fit with ribs 84 (which may be aspring clip or other retainer) formed on probe tip 1. In otherembodiments, other methods of affixing such a protective cap to probetip 1 are utilized. The protective cap may be removed from probe tip 1and sterilized in a typical autoclave, hot steam, chemiclave or othersterilizing system.

The thickness of the sapphire window should be less than the peakingheight of the probe in order to preserve the ability to detect peakingin accordance with the present invention, and preferably has a thicknessless than the critical height at which the source/receiver cones overlap(see FIGS. 4B and 4C). It also is believed that sapphire windows may bemanufactured in a reproducible manner, and thus any light attenuationfrom one cap to another may be reproducible. In addition, any distortionof the color/optical measurements produced by the sapphire window may becalibrated out by microprocessor 10.

Similarly, in other embodiments body 80 has a cap with a hole in thecenter (as opposed to a sapphire window), with the hole positioned overthe fiber optic source/receivers The cap with the hole serves to preventthe probe from coming into contact with the surface, thereby reducingthe risk of contamination. It should be noted that, with suchembodiments, the hole is positioned so that the light from/to the lightsource/receiver elements of the probe tip is not adversely affected bythe cap.

FIGS. 8A and 8B illustrate another embodiment of a removable probe tipthat may be used to reduce contamination in accordance with the presentinvention. As illustrated in FIG. 8A, probe tip 88 is removable, andincludes four (or a different number, depending upon the application)fiber optic connectors 90, which are positioned within optical guard 92coupled to connector 94. Optical guard 92 serves to prevent “cross talk”between adjacent fiber optics. As illustrated in FIG. 8B, in thisembodiment removable tip 88 is secured in probe tip housing 93 by way ofspring clip 96 (other removable retaining implements are utilized inother embodiments). Probe tip housing 93 may be secured to baseconnector 95 by a screw or other conventional fitting. It should benoted that, with this embodiment, different size tips may be providedfor different applications, and that an initial step of the process maybe to install the properly-sized (or fitted tip) for the particularapplication. Removable tip 88 also may be sterilized in a typicalautoclave, hot steam, chemiclave or other sterilizing system, ordisposed of. In addition, the entire probe tip assembly is constructedso that it may be readily disassembled for cleaning or repair. Incertain embodiments the light source/receiver elements of the removabletip are constructed of glass, silica or similar materials, therebymaking them particularly suitable for autoclave or similar hightemperature/pressure cleaning methods, which in certain otherembodiments the light source/receiver elements of the removable tip areconstructed of plastic or other similar materials, which may be of lowercost, thereby making them particularly suitable for disposable-typeremovable tips, etc.

In still other embodiments, a plastic, paper or other type shield (whichmay be disposable, cleanable/reusable or the like) may be used in orderto address any contamination concerns that may exist in the particularapplication. In such embodiments, the methodology may includepositioning such a shield over the probe tip prior to takingcolor/optical measurements, and may include removing anddisposing/cleaning the shield after taking color/optical measurements,etc.

A further embodiment of the present invention utilizing an alternateremovable probe tip will now be described with reference to FIGS.23A-23C. As illustrated in FIG. 23A, this embodiment utilizes removable,coherent light conduit 340 as a removable tip. Light conduit 340 is ashort segment of a light conduit that preferably may be a fused bundleof small fiber optics, in which the fibers are held essentially parallelto each other, and the ends of which are highly polished. Cross-section350 of light conduit 340 is illustrated in FIG. 23B. Light conduitssimilar to light conduit 340 have been utilized in what are known asborescopes, and also have been utilized in medical applications such asendoscopes.

Light conduit 340 in this embodiment serves to conduct light from thelight source to the surface of the object being measured, and also toreceive reflected light from the surface and conduct it to lightreceiver fiber optics 346 in probe handle 344. Light conduit 340 is heldin position with respect to fiber optics 346 by way or compression jaws342 or other suitable fitting or coupled that reliably positions lightconduit 340 so as to couple light effectively to/from fiber optics 346.Fiber optics 346 may be separated into separate fibers/light conduits348, which may be coupled to appropriate light sensors, etc., as withpreviously described embodiments.

In general, the aperture of the fiber optics used in light conduit 340may be chosen to match the aperture of the fiber optics for the lightsource and the light receivers or alternately the light conduit aperturecould be greater than or equal to the largest source or receiveraperture. Thus, the central part of the light conduit may conduct lightfrom the light source and illuminate the surface as if it constituted asingle fiber within a bundle of fibers. Similarly, the outer portion ofthe light conduit may receive reflected light and conduct it to lightreceiver fiber optics as if it constituted single fibers. Light conduit340 has ends that preferably are highly polished and cut perpendicular,particularly the end coupling light to fiber optics 346. Similarly, theend of fiber optics 346 abutting light conduit 340 also is highlypolished and cut perpendicular to a high degree of accuracy in order tominimize light reflection and cross talk between the light source fiberoptic and the light receiver fiber optics and between adjacent receiverfiber optics. Light conduit 340 offers significant advantages includingin the manufacture and installation of such a removable tip. Forexample, the probe tip need not be particularly aligned with the probetip holder; rather, it only needs to be held against the probe tipholder such as with a compression mechanism (such as with compressionjaws 342) so as to couple light effectively to/from fiber optics 346.Thus, such a removable tip mechanism may be implemented withoutalignment tabs or the like, thereby facilitating easy installation ofthe removable probe tip. Such an easy installable probe tip may thus beremoved and cleaned prior to installation, thereby facilitating use ofthe color/optical measuring apparatus by dentists, medical professionsor others working in an environment in which contamination may be aconcern. Light conduit 340 also may be implemented, for example, as asmall section of light conduit, which may facilitate easy and low costmass production and the like.

A further embodiment of such a light conduit probe tip is illustrated aslight conduit 352 in FIG. 23C. Light conduit 352 is a light conduit thatis narrower on one end (end 354) than the other end (end 356).Contoured/tapered light conduits such as light conduit 352 may befabricated by heating and stretching a bundle of small fiber optics aspart of the fusing process. Such light conduits have an additionalinteresting property of magnification or reduction. Such phenomenaresult because there are the same number of fibers in both ends. Thus,light entering narrow end 354 is conducted to wider end 356, and sincewider end 356 covers a larger area, it has a magnifying affect.

Light conduit 352 of FIG. 23C may be utilized in a manner similar tolight conduit 340 (which in general may be cylindrical) of FIG. 23A.Light conduit 352, however, measures smaller areas because of itsreduced size at end 354. Thus, a relatively larger probe body may bemanufactured where the source fiber optic is spaced widely from thereceiver fiber optics, which may provide an advantage in reduced lightreflection and cross talk at the junction, while still maintaining asmall probe measuring area. Additionally, the relative sizes of narrowend 354 of light conduit 352 may be varied. This enables the operator toselect the size/characteristic of the removable probe tip according tothe conditions in the particular application. Such ability to selectsizes of probe tips provides a further advantage in making opticalcharacteristics measurements in a variety of applications and operativeenvironments.

As should be apparent to those skilled in the art in view of thedisclosures herein, light conduits 340 and 356 of FIGS. 23A and 23C neednot necessarily be cylindrical/tapered as illustrated, but may be curvedsuch as for specialty applications, in which a curved probe tip may beadvantageously employed (such as in a confined or hard-to-reach place).It also should be apparent that light conduit 352 of FIG. 23C may bereversed (with narrow end 354 coupling light into fiber optics 346,etc., and wide end 356 positioned in order to take measurements) inorder to cover larger areas.

With reference to FIG. 9, a tristimulus embodiment will now bedescribed, which may aid in the understanding of, or may be used inconjunction with, certain embodiments disclosed herein. In general, theoverall system depicted in FIG. 1 and discussed in detail elsewhereherein may be used with this embodiment. FIG. 9 illustrates a crosssection of the probe tip fiber optics used in this embodiment.

Probe tip 100 includes central source fiber optic 106, surrounded by(and spaced apart from) three perimeter receiver fiber optics 104 andthree color receiver fiber optics 102. Three perimeter receiver fiberoptics 104 are optically coupled to neutral density filters and serve asheight/angle sensors in a manner analogous to the embodiment describeabove. Three color receiver fiber optics are optically coupled tosuitable tristimulus filters, such as red, green and blue filters. Withthis embodiment, a measurement may be made of tristimulus color valuesof the object, and the process described with reference to FIG. 6generally is applicable to this embodiment. In particular, perimeterfiber optics 104 may be used to detect simultaneous peaking or otherwisewhether the probe is perpendicular to the object being measured.

FIG. 10A illustrates another such embodiment, similar to the embodimentdiscussed with reference to FIG. 9. Probe tip 100 includes centralsource fiber optic 106, surrounded by (and spaced apart from) threeperimeter receiver fiber optics 104 and a plurality of color receiverfiber optics 102. The number of color receiver fiber optics 102, and thefilters associated with such receiver fiber optics 102, may be chosenbased upon the particular application. As with the embodiment of FIG. 9,the process described with reference to FIG. 6 generally is applicableto this embodiment.

FIG. 10B illustrates another such embodiment in which there are aplurality of receiver fiber optics that surround central source fiberoptic 240. The receiver fiber optics are arranged in rings surroundingthe central source fiber optic. FIG. 10B illustrates three rings ofreceiver fiber optics (consisting of fiber optics 242, 244 and 246,respectively), in which there are six receiver fiber optics per ring.The rings may be arranged in successive larger circles as illustrated tocover the entire area of the end of the probe, with the distance fromeach receiver fiber optic within a given ring to the central fiber opticbeing equal (or approximately so). Central fiber optic 240 is utilizedas the light source fiber optic and is connected to the light source ina manner similar to light source fiber optic 5 illustrated in FIG. 1.

The plurality of receiver fiber optics are each coupled to two or morefiber optics in a manner similar to the arrangement illustrated in FIG.1 for splicing connector 4. One fiber optic from such a splicingconnector for each receiver fiber optic passes through a neutral densityfilter and then to light sensor circuitry similar to the light sensorcircuitry illustrated in FIG. 3. A second fiber optic from the splicingconnector per receiver fiber optic passes through a Sharp CuttingWrattan Gelatin Filter (or notch filter as previously described) andthen to light sensor circuitry as discussed elsewhere herein. Thus, eachof the receiver fiber optics in the probe tip includes both colormeasuring elements and neutral light measuring or “perimeter” elements.

FIG. 10D illustrates the geometry of probe 260 (such as described above)illuminating an area on flat diffuse surface 272. Probe 260 createslight pattern 262 that is reflected diffusely from surface 272 inuniform hemispherical pattern 270. With such a reflection pattern, thereflected light that is incident upon the receiving elements in theprobe will be equal (or nearly equal) for all elements if the probe isperpendicular to the surface as described above herein.

FIG. 10C illustrates a probe illuminating rough surface 268 or a surfacethat reflects light unevenly. The reflected light will exhibit hot spotsor regions 266 where the reflected light intensity is considerablygreater than it is on other areas 264. The reflected light pattern willbe uneven when compared to a smooth surface as illustrate in FIG. 10D.

Since a probe as illustrated in FIG. 10B has a plurality of receiverfiber optics arranged over a large surface area, the probe may beutilized to determine the surface texture of the surface as well asbeing able to measure the color and translucency, etc., of the surfaceas described earlier herein. If the light intensity received by thereceiver fiber optics is equal for all fiber optics within a given ringof receiver fiber optics, then generally the surface is smooth. If,however, the light intensity of receiver fibers in a ring varies withrespect to each other, then generally the surface is rough. By comparingthe light intensities measured within receiver fiber optics in a givenring and from ring to ring, the texture and other characteristics of thesurface may be quantified.

FIG. 11 illustrates an embodiment of the present invention in whichlinear optical sensors and a color gradient filter are utilized insteadof light sensors 8 (and filters 22, etc.). Receiver fiber optics 7,which may be optically coupled to probe tip 1 as with the embodiment ofFIG. 1, are optically coupled to linear optical sensor 112 through colorgradient filter 110. In this embodiment, color gradient filter 110 mayconsist of series of narrow strips of cut-off type filters on atransparent or open substrate, which are constructed so as topositionally correspond to the sensor areas of linear optical sensor112. An example of a commercially available linear optical sensor 112 isTexas Instruments part number TSL213, which has 61 photo diodes in alinear array. Light receiver fiber optics 7 are arranged correspondinglyin a line over linear optical sensor 112. The number of receiver fiberoptics may be chosen for the particular application, so long as enoughare included to more or less evenly cover the full length of colorgradient filter 110. With this embodiment, the light is received andoutput from receiver fiber optics 7, and the light received by linearoptical sensor 112 is integrated for a short period of time (determinedby the light intensity, filter characteristics and desired accuracy).The output of linear array sensor 112 is digitized by ADC 114 and outputto microprocessor 116 (which may the same processor as microprocessor 10or another processor).

In general, with the embodiment of FIG. 11, perimeter receiver fiberoptics may be used as with the embodiment of FIG. 1, and in general theprocess described with reference to FIG. 6 is applicable to thisembodiment.

FIG. 12 illustrates an embodiment of the present invention in which amatrix optical sensor and a color filter grid are utilized instead oflight sensors 8 (and filters 22, etc.). Receiver fiber optics 7, whichmay be optically coupled to probe tip 1 as with the embodiment of FIG.1, are optically coupled to matrix optical sensor 122 through filtergrid 120. Filter grid 120 is a filter array consisting of a number ofsmall colored spot filters that pass narrow bands of visible light.Light from receiver fiber optics 7 pass through corresponding filterspots to corresponding points on matrix optical sensor 122. In thisembodiment, matrix optical sensor 122 may be a monochrome optical sensorarray, such as CCD-type or other type of light sensor element such asmay be used in a video camera. The output of matrix optical sensor 122is digitized by ADC 124 and output to microprocessor 126 (which may thesame processor as microprocessor 10 or another processor). Under controlof microprocessor 126, matrix optical sensor 126 collects data fromreceiver fiber optics 7 through color filter grid 120.

In general, with the embodiment of FIG. 12, perimeter receiver fiberoptics may be used as with the embodiment of FIG. 1, and in general theprocess described with reference to FIG. 6 also is applicable to thisembodiment.

In general with the embodiments of FIGS. 11 and 12, the color filtergrid may consist of sharp cut off filters as described earlier or it mayconsist of notch filters. As will be apparent to one skilled in the art,they may also be constructed of a diffraction grating and focusingmirrors such as those utilized in conventional monochromators.

As will be clear from the foregoing description, with the presentinvention a variety of types of spectral color/optical photometers (ortristimulus-type calorimeters) may be constructed, with perimeterreceiver fiber optics used to collect color/optical data essentiallyfree from height and angular deviations. In addition, in certainembodiments, the present invention enables color/optical measurements tobe taken at a peaking height from the surface of the object beingmeasured, and thus color/optical data may be taken without physicalcontact with the object being measured (in such embodiments, thecolor/optical data is taken only by passing the probe through region 1and into region 2, but without necessarily going into region 3 of FIGS.5A and 5B). Such embodiments may be utilized if contact with the surfaceis undesirable in a particular application. In the embodiments describedearlier, however, physical contact (or near physical contact) of theprobe with the object may allow all five regions of FIGS. 5A and 5B tobe utilized, thereby enabling measurements to be taken such thattranslucency information also may be obtained. Both types of embodimentsgenerally are within the scope of the invention described herein.

Additional description will now be provided with respect to cut-offfilters of the type described in connection with the preferredembodiment(s) of FIGS. 1 and 3 (such as filters 22 of FIG. 3). FIG. 13Aillustrates the properties of a single Kodak Sharp Cutting WrattenGelatin Filter discussed in connection with FIG. 3. Such a cut-offfilter passes light below a cut-off frequency (i.e., above a cut-offwavelength). Such filters may be manufactured to have a wide range ofcut-off frequencies/wavelengths. FIG. 13B illustrates a number of suchfilters, twelve in a preferred embodiment, with cut-offfrequencies/wavelengths chosen so that essentially the entire visibleband is covered by the collection of cut-off filters.

FIGS. 14A and 14B illustrate exemplary intensity measurements using acut-off filter arrangement such as illustrated in FIG. 13B, first in thecase of a white surface being measured (FIG. 14A), and also in the caseof a blue surface being measured (FIG. 14B). As illustrated in FIG. 14A,in the case of a white surface, the neutrally filtered perimeter fiberoptics, which are used to detect height and angle, etc., generally willproduce the highest intensity (although this depends at least in partupon the characteristics of the neutral density filters). As a result ofthe stepped cut-off filtering provided by filters having thecharacteristics illustrated in FIG. 13B, the remaining intensities willgradually decrease in value as illustrated in FIG. 14A. In the case of ablue surface, the intensities will decrease in value generally asillustrated in FIG. 14B. Regardless of the surface, however, theintensities out of the filters will always decrease in value asillustrated, with the greatest intensity value being the output of thefilter having the lowest wavelength cut-off value (i.e., passes allvisible light up to blue), and the lowest intensity value being theoutput of the filter having the highest wavelength cut-off (i.e., passesonly red visible light). As will be understood from the foregoingdescription, any color data detected that does not fit the decreasingintensity profiles of FIGS. 14A and 14B may be detected as anabnormality, and in certain embodiments detection of such a conditionresults in data rejection, generation of an error message or initiationof a diagnostic routine, etc.

Reference should be made to the FIGS. 1 and 3 and the relateddescription for a detailed discussion of how such a cut-off filterarrangement may be utilized in accordance with the present invention.

FIG. 15 is a flow chart illustrating audio tones that may be used incertain preferred embodiments of the present invention. It has beendiscovered that audio tones (such as tones, beeps, voice or the likesuch as will be described) present a particularly useful and instructivemeans to guide an operator in the proper use of a color measuring systemof the type described herein.

The operator may initiate a color/optical measurement by activation of aswitch (such as switch 17 of FIG. 1) at step 150. Thereafter, if thesystem is ready (set-up, initialized, calibrated, etc.), alower-the-probe tone is emitted (such as through speaker 16 of FIG. 1)at step 152. The system attempts to detect peak intensity P1 at step154. If a peak is detected, at step 156 a determination is made whetherthe measured peak P1 meets the applicable criteria (such as discussedabove in connection with FIGS. 5A, 5B and 6). If the measured peak P1 isaccepted, a first peak acceptance tone is generated at step 160. If themeasured peak P1 is not accepted, an unsuccessful tone is generated atstep 158, and the system may await the operator to initiate a furthercolor/optical measurement. Assuming that the first peak was accepted,the system attempts to detect peak intensity P2 at step 162. If a secondpeak is detected, at step 164 a determination is made whether themeasured peak P2 meets the applicable criteria. If the measured peak P2is accepted the process proceeds to color calculation step 166 (in otherembodiments, a second peak acceptance tone also is generated at step166). If the measured peak P2 is not accepted, an unsuccessful tone isgenerated at step 158, and the system may await the operator to initiatea further color/optical measurement. Assuming that the second peak wasaccepted, a color/optical calculation is made at step 166 (such as, forexample, microprocessor 10 of FIG. 1 processing the data output fromlight sensors 8, etc.). At step 168, a determination is made whether thecolor calculation meets the applicable criteria. If the colorcalculation is accepted, a successful tone is generated at step 170. Ifthe color calculation is not accepted, an unsuccessful tone is generatedat step 158, and the system may await the operator to initiate a furthercolor/optical measurement.

With unique audio tones presented to an operator in accordance with theparticular operating state of the system, the operator's use of thesystem may be greatly facilitated. Such audio information also tends toincrease operator satisfaction and skill level, as, for example,acceptance tones provide positive and encouraging feedback when thesystem is operated in a desired manner.

The color/optical measuring systems and methods in accordance with thepresent invention may be applied to particular advantage in the field ofdentistry, as will be more fully explained hereinafter. In particularthe present invention includes the use of such systems and methods tomeasure the color and other attributes of a tooth in order to prepare adental prosthesis or intraoral tooth-colored fillings, or to selectdenture teeth or to determine a suitable cement color forporcelain/resin prostheses. The present invention also provides methodsfor storing and organizing measured data such as in the form of apatient database.

FIG. 16A is a flow chart illustrating a general dental applicationprocess flow for use of the color/optical measuring systems and methodsin accordance with the present invention. At step 200, the color/opticalmeasuring system may be powered-up and stabilized, with any requiredinitialization or other setup routines performed. At step 200, anindication of the system status may be provided to the operator, such asthrough LCD 14 or speaker 16 of FIG. 1. Also at step 200, the probe tipmay be shielded or a clean probe tip may be inserted in order to reducethe likelihood of contamination (see, e.g., FIGS. 7A to 8B and relateddescription). In other embodiments, a plastic or other shield may alsobe used (which may be disposable, cleanable/reusable, etc., aspreviously described), so long as it is constructed and/or positioned soas to not adversely affect the measurement process.

At step 202, the patient and the tooth to be measured are prepared. Anyrequired cleaning or other tooth preparation would be performed at step202. Any required patient consultation about the type of prosthesis orarea of a tooth to be matched would be performed at (or before) step202. In certain embodiments, a positioning device is prepared at step202, such as is illustrated in FIGS. 17A and 17B. In such embodiments,for example, a black or other suitably-colored material 282, which mayadhere to tooth 280 (such as with a suitable adhesive), is formed tohave opening 281 larger than the diameter of the measuring probe, withopening 281 centered on the area of tooth 280 to be measured. Thematerial of positioning device 282 is formed in a manner to fit on/overtooth 280 (such as over the incisal edge of tooth 280 and/or over one ormore adjacent teeth) so that it may be placed on/over tooth 280 in arepeatable manner. Such a positioning device may serve to ensure thatthe desired area of tooth 280 is measured, and also allows for repeatmeasurements of the same area for purposes of confirmation, fluorescencemeasurement, or other optical measurement, or the like. Any otherpre-measurement activities may be performed at (or before) step 202.

At step 204, the operator (typically a dentist or other dentalprofessional) moves the probe towards the area of the tooth to bemeasured. This process preferably is conducted in accordance with themethodology described with reference to FIGS. 5A, 5B and 6, andpreferably is accompanied by audio tones such as described withreference to FIG. 15. With the present invention, the operator mayobtain color and translucency data, etc., for example, from a desiredarea of the tooth to be measured. During step 204, an acceptedcolor/optical measurement is made, or some indication is given to theoperator that the measurement step needs to be repeated or some otheraction taken. After an accepted color/optical measurement is made atstep 204, for example, the dentist may operate on the desired tooth orteeth or take other action. Before or after such action, additionalmeasurements may be taken as needed (see, e.g., FIG. 18 and relateddescription).

Upon successful completion of one or more measurements taken at step204, the process proceeds to step 206. At step 206, any data conversionor processing of data collected at step 204 may be performed. Forexample, in the embodiment of FIG. 1, detailed color spectrum andtranslucency information may be generated. In a particular dentalapplication, however, it may be that a dental lab, for example, requiresthat the color be presented in Munsell format (i.e., chroma, hue andvalue), RGB values, XYZ coordinates, CIELAB values, Hunter values, orsome other color data format. With the spectral/color informationproduced by the present invention, data may be converted to such formatsthrough conventional math, for example. Such math may be performed bymicroprocessor 10 or computer 13A of FIG. 1, or in some other manner. Italso should be noted that, in certain embodiments, the data produced atstep 204 in accordance with the present invention may be used directlywithout data conversion. In such embodiments, step 206 may be omitted.In other embodiments, step 206 consists of data formatting, such aspreparing the data for reproduction in hard copy, pictorial or otherform, or for transmission as facsimile or modem data. Finally, incertain embodiments a translucency factor is computed in a formatsuitable for the particular application. In yet other embodiments, asurface texture or detail factor is computed in a format suitable forthe particular application. In yet other embodiments, a surface glossfactor is computed in a format suitable for the particular application.

At step 208, a matching is optionally attempted between the dataproduced at steps 204 and 206 (if performed) and a desired color (inother embodiments, the process may proceed from 204 directly to 210, oralternatively steps 206 and 208 may be combined). For example, a numberof “shade guides” are available in the market, some of which are knownin the industry as Vita shade guides, Bioform shade guides or othercolor matching standards, guides or references or custom shade guides.In certain preferred embodiments, a lookup table is prepared and loadedinto memory (such as memory associated with microprocessor 10 orcomputer 13A of FIG. 1), and an attempt is made to the closest match ormatches of the collected data with the known shade guides, custom shadeguides or reference values. In certain embodiments, a translucencyfactor and/or gloss factor and/or a surface texture or detail factoralso is used in an effort to select the best possible match.

In a particular aspect of certain embodiments of the present invention,at step 208 a material correlation lookup table is accessed. Based onthe color and translucency data obtained at step 204, a proposed recipeof materials, pigments or other instruction information is prepared fora prosthesis or filling, etc., of the desired color and translucency,etc. With the detailed color and other information made available inaccordance with the present invention, a direct correlation with therelevant constituent materials may be made. In still other embodiments,such information is made available to an automated mixing ormanufacturing machine for preparation of prosthesis or material of thedesired color and translucency, etc., as more fully described elsewhereherein.

At step 210, based on the results of the preceding steps, theprosthesis, denture, intraoral tooth-colored filling material or otheritems are prepared. This step may be performed at a dental lab, or, incertain embodiments, at or near the dental operatory. For remotepreparation, relevant data produced at steps 204, 206 and/or 208 may besent to the remote lab or facility by hardcopy, facsimile or modem orother transmission. What should be understood from the foregoing isthat, based on data collected at step 204, a prosthesis may be preparedof a desirable color and/or other optical characteristic at step 210.

At step 212, the prosthesis or other material prepared at step 210 maybe measured for confirmation purposes, again preferably conducted inaccordance with the methodology described with reference to FIGS. 5A, 5Band 6, and preferably accompanied by audio tones such as described withreference to FIG. 15. A re-measure of the tooth in the patient's mouth,etc. also may be made at this step for confirmation purposes. If theconfirmation process gives satisfactory results, the prosthesis,denture, composite filling or other material may be preliminarilyinstalled or applied in the patient at step 214. At step 216, are-measure of the prosthesis, denture, composite filling or othermaterials optionally may be made. If the results of step 216 areacceptable, then the prosthesis may be more permanently installed orapplied in the patient at step 218. If the results of step 216 are notacceptable, the prosthesis may be modified and/or other of the stepsrepeated as necessary in the particular situation.

With reference to FIG. 16B, a further embodiment of the presentinvention will be explained. With this embodiment, an instrument andmethod such as previously described may be advantageously utilized toprepare a tooth to receive a prosthesis.

A dental prosthesis such as a crown or a laminate has optical propertiesthat are determined by a number of factors. Determining factors includethe material of the prosthesis, along with the cement utilized to bondthe prosthesis to the tooth and the underlying optical properties of thetooth itself. For example, in the preparation of a tooth for a laminate,the thickness of the laminate combined with the bonding cement and thecolor of the underlying prepared tooth all contribute to the finaloptical properties of the prosthesis. In order to prepare an optimumprosthesis such as from an esthetic standpoint, the dentist may need toprepare the tooth for the laminate by removing material from the tooth.The final desired esthetic color, shape and contours of the toothdetermines the amount of material needed to be removed from the tooth,which determines the final thickness of the laminate, and in significantpart may determine whether or not the final restoration will have adesired and esthetically pleasing result as compared to neighboringteeth. By measuring the color of the neighboring teeth, and by measuringthe color of the underlying tooth being prepared for the laminate, theamount of tooth material to be removed, or the range of material thatshould be removed, may be determined and reported to the dentist as thetooth is being prepared.

At step 201, the process is commenced. Any initial calibration or otherpreparatory steps may be undertaken. At step 203, the dentist maymeasure the optical properties including color of one or moreneighboring teeth. At step 205, the dentist may measure the opticalproperties including color of the tooth receiving the prosthesis. Atstep 207, a first amount of material to be removed is calculated orestimated (such as by microprocessor 10, computer 13A or other suitablecomputing device). The first amount is determined based on known colorproperties of the available laminates, the estimated thickness of thelaminate, and the color of the tooth to receive the laminate. If, forexample, the tooth to receive the laminate is dark to the degree that anesthetically pleasing laminate likely cannot be produced (based on therange of color/optical characteristics of the known availablelaminates), then an estimate is made of how much material should beremoved such that a thicker laminate will result in a desired andesthetically pleasing result. At step 209 the dentist removes the firstamount of material (or approximately such amount) from the tooth (usingknown removal techniques, etc.). At step 211, the dentist may againmeasure the optical properties including color of the tooth receivingthe prosthesis. At step 213, a calculation or estimation is made (in amanner analogous to step 207) of whether additional material should beremoved, and, if so, how much. At step 215, if needed, additionalmaterial is removed, with steps 211, 213 and 215 repeated as necessary.In preferred embodiments, based on known/measured/empirical dataanalysis of color/optical properties of teeth, at steps such as steps205 and 211, a comparison or assessment may be made of whether the toothbeing prepared is getting too near the pulp (such as by detection of apink color, for example). Based on such threshold or other typecriteria, the dentist may be alerted that further material should not beremoved in order to minimize exposure of the pulp and damage of thetooth. At step 217, if it is determined at step 213 that a desirable andesthetically pleasing laminate may be produced, such laminatepreparation steps are conducted.

Similar steps could be taken in other industrial endeavors, such aspainting or other finishes, etc.

In another particular aspect of the present invention, for example, dataprocessing such as illustrated in FIG. 18 may be taken in conjunctionwith the processes of FIGS. 16A and/or 16B. At step 286, client databasesoftware is run on a computing device, such as computer 13A of FIG. 1.Such software may include data records for each patient, includingfields storing the history of dental services performed on the patient,information regarding the status or condition of the patient's teeth,billing, address and other information. Such software may enter a modeby which it is in condition to accept color or other data taken inaccordance with the present invention.

At step 288, for example, the dentist or other dental professional mayselect parameters for a particular tooth of the patient to be measured.Depending on the size and condition of the tooth (such as color gradientor the like), the dentist may sector the tooth into one or more regions,such as a grid. Thus, for example, in the case of tooth for which it isdecided to take four measurements, the tooth may be sectored into fourregions. Such parameters, which may include a pictorial representationon the computer of the tooth sectored into four regions (such as by gridlines), along with tooth identification and patient information may beentered into the computer at this time.

At step 290, one or more measurements of the tooth may be taken, such aswith a system and method as described in connection with FIGS. 1, 5A, 5Band/or 6. The number of such measurements preferably is associated withthe parameters entered at step 288. Thereafter, at step 292, the datacollected from the measurement(s) may be sent to the computer forsubsequent processing. As an illustrative example, four color/opticalmeasurements may be taken (for the four regions of the tooth in theabove example) and sent to the computer, with the data for the fourcolor/optical measurements (such as RGB or other values) associated withthe four regions in accordance with the entered parameters. Also, as anexample, the displayed pictorial representation of the tooth may haveoverlaid thereof data indicative of the color/optical measurement(s). Atstep 294, such as after completion of color/optical measurements on theparticular patient, the data collected during the process may beassociatively stored as a part of the patient's dental records in thedata base. In embodiments accompanied by use of an intraoral camera, forexample (see, e.g., FIG. 19 and related description), captured images ofone or more of the patient's teeth also may be associatively stored aspart of the patient's dental records. In certain embodiments, a picturecaptured by the intraoral camera is overlaid with grid or sector lines(such as may be defined in step 288), with color or other data measuredas described herein also overlaid over the captured image. In such amanner, the color or other data may be electronically and visuallyassociated with a picture of the particular measured tooth, therebyfacilitating the use of the system and the understanding of thecollected data. In still other embodiments, all such captured image andcolor measurement records include a time and/or date, so that a recordof the particular history of a particular tooth of a particular patientmay be maintained. See FIGS. 24 to 26 and 32 to 34 and relateddescription for additional embodiments utilizing an intraoral camera,etc., in accordance with the present invention.

In yet another particular aspect of the present invention, a measuringdevice and method (such as described elsewhere herein) may be combinedwith an intraoral camera and other implements. As illustrated in FIG.19, control unit 300 contains conventional electronics and circuitry,such as power supplies, control electronics, light sources and the like.Coupled to control unit 300 is intraoral camera 301 (for viewing, andcapturing images of, a patient's tooth or mouth, etc.), curing light 302(such as for curing light-cured intraoral filling material), measuringdevice 304 (such as described elsewhere herein), and visible light 306(which may be an auxiliary light for intraoral examinations and thelike). With such embodiments, color, translucency, fluorescence, gloss,surface texture and/or other data collected for a particular tooth frommeasuring device 304 may be combined with images captured by intraoralcamera 301, with the overall examination and processing of the patientfacilitated by having measuring device 304, intraoral camera 301, curinglight 302 and visible light 306 integrated into a single unit. Suchintegration serves to provide synergistic benefits in the use of theinstruments, while also reducing costs and saving physical space. Inanother particular aspect of such embodiments, the light source formeasuring device 304 and intraoral camera 301 are shared, therebyresulting in additional benefits.

Further embodiments of the present invention will now be described withreference to FIGS. 20 to 23. The previously described embodimentsgenerally rely on movement of the probe with respect to the object/toothbeing measured. While such embodiments provide great utility in manyapplications, in certain applications, such as robotics, industrialcontrol, automated manufacturing, etc. (such as positioning the objectand/or the probe to be in proximity to each other, detectingcolor/optical properties of the object, and then directing the object,e.g., sorting, based on the detected color/optical properties, forfurther industrial processing, packaging, etc.) it may be desired tohave the measurement made with the probe held or positionedsubstantially stationary above the surface of the object to be measured(in such embodiments, the positioned probe may not be handheld as withcertain other embodiments). Such embodiments also may have applicabilityin the field of dentistry (in such applications, “object” generallyrefers to a tooth, etc.).

FIG. 20 illustrates such a further embodiment. The probe of thisembodiment includes a plurality of perimeter sensors and a plurality ofcolor sensors coupled to receivers 312-320. The color sensors andrelated components, etc., may be constructed to operate in a manneranalogous to previously described embodiments. For example, fiber opticcables or the like may couple light from source 310 that is received byreceivers 312-320 to sharp cut-off filters or to notch filters, with thereceived light measured over precisely defined wavelengths (see, e.g.,FIGS. 1, 3 and 11-14 and related description). Color/opticalcharacteristics of the object may be determined from the plurality ofcolor sensor measurements, which may include three such sensors in thecase of a tristimulus instrument, or 8, 12, 15 or more color sensors fora more full bandwidth system (the precise number may be determined bythe desired color resolution, etc.).

With this embodiment, a relatively greater number of perimeter sensorsare utilized (as opposed, for example, to the three perimeter sensorsused in certain preferred embodiments of the present invention). Asillustrated in FIG. 20, a plurality of triads of receivers 312-320coupled to perimeter sensors are utilized, where each triad in thepreferred implementation consists of three fiber optics positioned equaldistance from light source 310, which in the preferred embodiment is acentral light source fiber optic. The triads of perimeterreceivers/sensors may be configured as concentric rings of sensorsaround the central light source fiber optic. In FIG. 20, ten such triadrings are illustrated, although in other embodiments a lesser or greaternumber of triad rings may be utilized, depending upon the desiredaccuracy and range of operation, as well as cost considerations and thelike.

The probe illustrated in FIG. 20 may operate within a range of heights(i.e., distances from the object being measured). As with earlierembodiments, such height characteristics are determined primarily by thegeometry and constituent materials of the probe, with the spacing of theminimal ring of perimeter sensors determining the minimal height, andthe spacing of the maximal ring of perimeter sensors determining themaximum height, etc. It therefore is possible to construct probes ofvarious height ranges and accuracy, etc., by varying the number ofperimeter sensor rings and the range of ring distances from the centralsource fiber optic. It should be noted that such embodiments may beparticularly suitable when measuring similar types of materials, etc.

As described earlier, the light receiver elements for the plurality ofreceivers/perimeter sensors may be individual elements such as TexasInstruments TSL230 light-to-frequency converters, or may be constructedwith rectangular array elements or the like such as may be found in aCCD camera. Other broadband-type of light measuring elements areutilized in other embodiments. Given the large number of perimetersensors used in such embodiments (such as 30 for the embodiment of FIG.16), an array such as CCD camera-type sensing elements may be desirable.It should be noted that the absolute intensity levels of light measuredby the perimeter sensors is not as critical to such embodiments of thepresent invention; in such embodiments differences between the triads ofperimeter light sensors are advantageously utilized in order to obtainoptical measurements.

Optical measurements may be made with such a probe byholding/positioning the probe near the surface of the object beingmeasured (i.e., within the range of acceptable heights of the particularprobe). The light source providing light to light source 310 is turnedon and the reflected light received by receivers 312-320 (coupled to theperimeter sensors) is measured. The light intensity of the rings oftriad sensors is compared. Generally, if the probe is perpendicular tothe surface and if the surface is flat, the light intensity of the threesensors of each triad should be approximately will be equal. If theprobe is not perpendicular to the surface or if the surface is not flat,the light intensity of the three sensors within a triad will not beequal. It is thus possible to determine if the probe is perpendicular tothe surface being measured, etc. It also is possible to compensate fornon-perpendicular surfaces by mathematically adjusting the lightintensity measurements of the color sensors with the variance inmeasurements of the triads of perimeters sensors.

Since the three sensors forming triads of sensors are at differentdistances (radii) from central light source 310, it is expected that thelight intensities measured by light receivers 312-320 and the perimetersensors will vary. For any given triad of sensors, as the probe is movedcloser to the surface, the received light intensity will increase to amaximum and then sharply decrease as the probe is moved closer to thesurface. As with previously-described embodiments, the intensitydecreases rapidly as the probe is moved less than the peaking height anddecreases rapidly to zero or almost zero for opaque objects. The valueof the peaking height depends principally upon the distance of theparticular receiver from light source 310. Thus, the triads of sensorswill peak at different peaking heights. By analyzing the variation inlight values received by the triads of sensors, the height of the probecan be determined. Again, this is particularly true when measuringsimilar types of materials. As discussed earlier, comparisons withpreviously-stored data also may be utilized to made such determinationsor assessments, etc.

The system initially is calibrated against a neutral background (e.g., agray background), and the calibration values are stored in non-volatilememory (see, e.g., processor 10 of FIG. 1). For any given color orintensity, the intensity for the receivers/perimeter sensors(independent of distance from the central source fiber optic) in generalshould vary equally. Hence, a white surface should produce the highestintensities for the perimeter sensors, and a black surface will producethe lowest intensities. Although the color of the surface will affectthe measured light intensities of the perimeter sensors, it shouldaffect them substantially equally. The height of the probe from thesurface of the object, however, will affect the triads of sensorsdifferently. At the minimal height range of the probe, the triad ofsensors in the smallest ring (those closest to the source fiber optic)will be at or about their maximal value. The rest of the rings of triadswill be measuring light at intensities lower than their maximal values.As the probe is raised/positioned from the minimal height, the intensityof the smallest ring of sensors will decrease and the intensity of thenext ring of sensors will increase to a maximal value and will thendecrease in intensity as the probe is raised/positioned still further.Similarly for the third ring, fourth ring and so on. Thus, the patternof intensities measured by the rings of triads will be height dependent.In such embodiments, characteristics of this pattern may be measured andstored in non-volatile RAM look-up tables (or the like) for the probe bycalibrating it in a fixture using a neutral color surface. Again, theactual intensity of light is not as important in such embodiments, butthe degree of variance from one ring of perimeter sensors to another is.

To determine a measure of the height of the probe from the surface beingmeasured, the intensities of the perimeter sensors (coupled to receivers312-320) is measured. The variance in light intensity from the innerring of perimeter sensors to the next ring and so on is analyzed andcompared to the values in the look-up table to determine the height ofthe probe. The determined height of the probe with respect to thesurface thus may be utilized by the system processor to compensate forthe light intensities measured by the color sensors in order to obtainreflectivity readings that are in general independent of height. As withpreviously described embodiments, the reflectivity measurements may thenbe used to determine optical characteristics of the object beingmeasured, etc.

It should be noted that audio tones, such as previously described, maybe advantageously employed when such an embodiment is used in a handheldconfiguration. For example, audio tones of varying pulses, frequenciesand/or intensities may be employed to indicate the operational status ofthe instrument, when the instrument is positioned within an acceptablerange for color measurements, when valid or invalid color measurementshave been taken, etc. In general, audio tones as previously describedmay be adapted for advantageous use with such further embodiments.

FIG. 21 illustrates a further such embodiment of the present invention.The preferred implementation of this embodiment consists of a centrallight source 310 (which in the preferred implementation is a centrallight source fiber optic), surrounded by a plurality of light receivers322 (which in the preferred implementation consists of three perimeterlight receiver fiber optics). The three perimeter light receiver fiberoptics, as with earlier described embodiments, may be each spliced intoadditional fiber optics that pass to light intensity receivers/sensors,which may be implemented with Texas Instruments TSL230 light tofrequency converters as described previously. One fiber of eachperimeter receiver is coupled to a sensor and measured full band width(or over substantially the same bandwidth) such as via a neutral densityfilter, and other of the fibers of the perimeter receivers are coupledto sensors so that the light passes through sharp cut off or notchfilters to measure the light intensity over distinct frequency ranges oflight (again, as with earlier described embodiments). Thus, there arecolor light sensors and neutral “perimeter” sensors as with previouslydescribed embodiments. The color sensors are utilized to determine thecolor or other optical characteristics of the object, and the perimetersensors are utilized to determine if the probe is perpendicular to thesurface and/or are utilized to compensate for non-perpendicular angleswithin certain angular ranges.

In the embodiment of FIG. 21, the angle of the perimeter sensor fiberoptics is mechanically varied with respect to the central source fiberoptic. The angle of the perimeter receivers/sensors with respect to thecentral source fiber optic is measured and utilized as describedhereinafter. An exemplary mechanical mechanism, the details of which arenot critical so long as desired, control movement of the perimeterreceivers with respect to the light source is obtained, is describedwith reference to FIG. 22.

The probe is held within the useful range of the instrument (determinedby the particular configuration and construction, etc.), and a colormeasurement is initiated. The angle of the perimeter receivers/sensorswith respect to the central light source is varied from parallel topointing towards the central source fiber optic. While the angle isbeing varied, the intensities of the light sensors for the perimetersensors (e.g., neutral sensors) and the color sensors is measured andsaved along with the angle of the sensors at the time of the lightmeasurement. The light intensities are measured over a range of angles.As the angle is increased the light intensity will increase to a maximumvalue and will then decrease as the angle is further increased. Theangle where the light values is a maximum is utilized to determine theheight of the probe from the surface. As will be apparent to thoseskilled in the art based on the teachings provided herein, with suitablecalibration data, simple geometry or other math, etc., may be utilizedto calculate the height based on the data measured during variation ofthe angle. The height measurement may then be utilized to compensate forthe intensity of the color/optical measurements and/or utilized tonormalize color values, etc.

FIG. 22 illustrates an exemplary embodiment of a mechanical arrangementto adjust and measure the angle of the perimeter sensors. Each perimeterreceiver/sensor 322 is mounted with pivot arm 326 on probe frame 328.Pivot arm 326 engages central ring 332 in a manner to form a cammechanism. Central ring 332 includes a groove that holds a portion ofpivot arm 326 to form the cam mechanism. Central ring 332 may be movedperpendicular with respect to probe frame 328 via linear actuator 324and threaded spindle 330. The position of central ring 332 with respectto linear actuator 324 determines the angle of perimeterreceivers/sensors 322 with respect to light source 310. Such angularposition data vis-a-vis the position of linear actuator 324 may becalibrated in advance and stored in non-volatile memory, and later usedto produce color/optical characteristic measurement data as previouslydescribed.

Referring now to FIG. 24, a further embodiment of the present inventionwill be explained.

Intraoral reflectometer 380, which may be constructed as describedabove, includes probe 381. Data output from reflectometer 380 is coupledto computer 384 over bus 390 (which may be a standard serial or parallelbus, etc.). Computer 384 includes a video freeze frame capability andpreferably a modem. Intraoral camera 382 includes handpiece 383 andcouples video data to computer 384 over bus 392. Computer 384 is coupledto remote computer 386 over telecommunication channel 388, which may bea standard telephone line, ISDN line, a LAN or WAN connection, etc. Withsuch an embodiment, video measurements may be taken of one or more teethby intraoral camera 382, along with optical measurements taken byintraoral reflectometer 380. Computer 384 may store still picture imagestaken from the output of intraoral camera 382.

Teeth are known to have variations in color from tooth to tooth, andteeth are known to have variations in color over the area of one tooth.Intraoral cameras are known to be useful for showing the details ofteeth. Intraoral cameras, however, in general have poor colorreproducibility. This is due to variations in the camera sensingelements (from camera to camera and over time etc.), in computermonitors, printers, etc. As a result of such variations, it presently isnot possible to accurately quantify the color of a tooth with anintraoral camera. With the present embodiment, measuring and quantifyingthe color or other optical properties of teeth may be simplified throughthe use of an intraoral reflectometer in accordance with the presentinvention, along with an intraoral camera.

In accordance with this embodiment, the dentist may capture a stillpicture of a tooth and its adjacent teeth using the freeze frame featureof computer 384. Computer 384, under appropriate software and operatorcontrol, may then “postureize” the image of the tooth and its adjacentteeth, such as by limiting the number of gray levels of the luminancesignal, which can result in a color image that shows contours ofadjacent color boundaries. As illustrated in FIG. 25, such apostureization process may result in teeth 396 being divided intoregions 398, which follow color contours of teeth 396. As illustrated,in general the boundaries will be irregular in shape and follow thevarious color variations found on particular teeth.

With teeth postureized as illustrated in FIG. 25, computer 384 may thenhighlight (such as with a colored border, shading, highlight or thelike) a particular color region on a tooth to be measured, and then thedentist may then measure the highlighted region with intraoralreflectometer 380. The output of intraoral reflectometer 380 is input tocomputer 384 over bus 390, and computer 384 may store in memory or on ahard disk or other storage medium the color/optical data associated withthe highlighted region. Computer 384 may then highlight another regionand continue the process until color/optical data associated with alldesired highlighted regions have been stored in computer 384. Suchcolor/optical data may then be stored in a suitable data base, alongwith the video image and postureized video image of the particularteeth, etc.

Computer 384 may then assess if the measured value of a particular colorregion is consistent with color measurements for adjacent color regions.If, for example, a color/optical measurement for one region indicates adarker region as compared to an adjacent region, but the postureizedimage indicates that the reverse should be true, then computer 384 maynotify the dentist (such as with an audio tone) that one or more regionsshould be re-measured with intraoral reflectometer 380. Computer 384 maymake such relative color determinations (even though the color valuesstored in computer 384 from the freeze frame process are not true colorvalues) because the variations from region to region should follow thesame pattern as the color/optical measurements taken by intraoralreflectometer 380. Thus, if one region is darker than its neighbors,then computer 384 will expect that the color measurement data fromintraoral reflectometer 380 for the one region also will be darkerrelative to color measurement data for the neighboring regions, etc.

As with the optical characteristics measurement data and captured imagesdiscussed previously, the postureized image of the teeth, along with thecolor/optical measurement data for the various regions of the teeth, maybe conveniently stored, maintained and accessed as part of the patientdental records. Such stored data may be utilized advantageously increating dental prosthesis that more correctly match the colors/regionsof adjacent teeth. Additionally, in certain embodiments, such dataimages are used in conjunction with smile analysis software to furtheraid in the prosthesis preparation.

In a further refinement to the foregoing embodiment, computer 384preferably has included therein, or coupled thereto, a modem. With sucha modem capability (which may be hardware or software), computer 384 maycouple data to remote computer 386 over telecommunication channel 388.For example, remote computer 386 may be located at a dental laboratoryremotely located. Video images captured using intraoral camera 382 andcolor/optical data collected using intraoral reflectometer may betransmitted to a dental technician (for example) at the remote location,who may use such images and data to construct dental prosthesis.Additionally, computer 384 and remote computer 386 may be equipped withan internal or external video teleconference capability, therebyenabling a dentist and a dental technician or ceramist, etc., to have alive video or audio teleconference while viewing such images and/ordata.

For example, a live teleconference could take place, whereby the dentaltechnician or ceramist views video images captured using intraoralcamera 383, and after viewing images of the patient's teeth and facialfeatures and complexion, etc., instruct the dentist as to which areas ofthe patient's teeth are recommended for measurement using intraoralreflectometer 380. Such interaction between the dentist and dentaltechnician or ceramist may occur with or without postureization aspreviously described. Such interaction may be especially desirable at,for example, a try-in phase of a dental prosthesis, when minor changesor subtle characterizations may be needed in order to modify theprosthesis for optimum esthetic results.

A still further refinement may be understood with reference to FIG. 26.As illustrated in FIG. 26, color calibration chart 404 could be utilizedin combination with various elements of the previously describedembodiments, including intraoral camera 382. Color calibration chart 404may provide a chart of known color values, which may be employed, forexample, in the video image to further enhance correct skin tones ofpatient 402 in the displayed video image. As the patient's gingivaltissue, complexion and facial features, etc., may influence the finalesthetic results of a dental prosthesis, such a color calibration chartmay be desirably utilized to provide better esthetic results.

As an additional example, such a color calibration chart may be utilizedby computer 384 and/or 386 to “calibrate” the color data within acaptured image to true or known color values. For example, colorcalibration chart 404 may include one or more orientation markings 406,which may enable computers 384 and/or 386 to find and position colorcalibration chart 404 within a video frame. Thereafter, computers 384and/or 386 may then compare “known” color data values from colorcalibration chart (data indicative of the colors within colorcalibration chart 404 and their position relative to orientation mark ormarkings 406 are stored within computers 384 and/or 386, such as in alookup table, etc.) with the colors captured within the video image atpositions corresponding to the various colors of color calibration chart404. Based on such comparisons, computers 384 and/or 386 may coloradjust the video image in order to bring about a closer correspondencebetween the colors of the video image and known or true colors fromcolor calibration chart 404.

In certain embodiments, such color adjusted video data may be used inthe prosthesis preparation process, such as to color adjust the videoimage (whether or not postureized) in conjunction with color/opticaldata collected using intraoral reflectometer 380 (for example, asdescribed above or using data from intraoral reflectometer 380 tofurther color adjust portions of the video image), or to add subtlecharacterizations or modifications to a dental prosthesis, or to evenprepare a dental prosthesis, etc. While not believed to be as accurate,etc. as color/optical data collected using intraoral reflectometer 380,such color adjusted video data may be adequate in certain applications,environments, situations, etc., and such color adjusted video data maybe utilized in a similar manner to color data taken by a device such asintraoral reflectometer 380, including, for example, prosthesispreparation, patient data collection and storage, materials preparation,such as described elsewhere herein.

It should be further noted that color calibration chart 404 may bespecifically adapted (size, form and constituent materials, etc.) to bepositioned inside of the patient's mouth to be placed near the tooth orteeth being examined, so as to be subject to the same or nearly the sameambient lighting and environmental conditions, etc., as is the tooth orteeth being examined. It also should further be noted that theutilization of color calibration chart 404 to color correct video imagedata with a computer as provided herein also may be adapted to be usedin other fields, such as medical, industrial, etc., although its noveland advantageous use in the field of dentistry as described herein is ofparticular note and emphasis herein.

FIG. 27 illustrates a further embodiment of the present invention, inwhich an intraoral reflectometer in accordance with the presentinvention may be adapted to be mounted on, or removably affixed to, adental chair. An exemplary dental chair arrangement in accordance withthe present invention includes dental chair 410 is mounted on base 412,and may include typical accompaniments for such chairs, such as footcontrol 414, hose(s) 416 (for suction or water, etc.), cuspidor andwater supply 420 and light 418. A preferably movable arm 422 extends outfrom support 428 in order to provide a conveniently locatable support430 on which various dental instruments 424 are mounted or affixed in aremovable manner. Bracket table 426 also may be included, on which adentist may position other instruments or materials. In accordance withthis embodiment, however, instruments 424 include an intraoralreflectometer in accordance with the present invention, which isconveniently positioned and removably mounted/affixed on support 430, sothat color/optical measurements, data collection and storage andprosthesis preparation may be conveniently carried out by the dentist.As opposed to large and bulky prior art instruments, the presentinvention enables an intraoral reflectometer for collectingcolor/optical data, in some embodiments combined or utilized with anintraoral camera as described elsewhere herein, which may be readilyadapted to be positioned in a convenient location on a dental chair.Such a dental chair also may be readily adapted to hold otherinstruments, such as intraoral cameras, combined intraoralcamera/reflectors, drills, lights, etc.

With the foregoing as background, various additional preferredembodiments utilizing variable aperture receivers in order to measure,for example, the degree of gloss of the surface will now be describedwith references to FIGS. 28A to 30B. Various of the electronics andspectrophotometer/reflectometer implements described above will beapplicable to such preferred embodiments.

Referring to FIG. 28A, a probe utilizing variable aperture receiverswill now be described. In FIG. 28A, source A 452 represents a sourcefiber optic of a small numerical aperture NA, 0.25 for example;receivers B 454 represent receiver fiber optics of a wider numericalaperture, 0.5 for example; receivers C 456 represent receiver fiberoptics of the same numerical aperture as source A but is shown with asmaller core diameter; and receivers D 458 represent receiver fiberoptics of a wider numerical aperture, 0.5 for example.

One or more of receiver(s) B 454 (in certain embodiments one receiver Bmay be utilized, while in other embodiments a plurality of receivers Bare utilized, which may be circularly arranged around source A, such as6 or 8 such receivers B) pass to a spectrometer (see, e.g., FIGS. 1, 3,11, 12, configured as appropriate for such preferred embodiments).Receiver(s) B 454 are used to measure the spectrum of the reflectedlight. Receivers C 456 and D 458 pass to broad band (wavelength) opticalreceivers and are used to correct the measurement made by receiver(s) B.Receivers C 456 and D 458 are used to correct for and to detect whetheror not the probe is perpendicular to the surface and to measure/assessthe degree of specular versus diffuse reflection (the coefficient ofspecular reflection, etc.) and to measure the translucency of thematerial/object.

FIG. 28B illustrates a refinement of the embodiment of FIG. 28A, inwhich receivers B 454 are replaced by a cylindrical arrangement ofclosely packed, fine optical fibers 454A, which generally surround lightsource 452 as illustrated. The fibers forming the cylindricalarrangement for receivers B 454, are divided into smaller groups offibers and are presented, for example, to light sensors 8 shown in FIG.1. The number of groups of fibers is determined by the number of lightsensors. Alternately, the entire bundle of receiver fibers B 454 ispresented to a spectrometer such as a diffraction grating spectrometerof conventional design. As previously described, receivers C 456 and D458 may be arranged on the periphery thereof. In certain embodiments,receivers C and D may also consist of bundles of closely packed, fineoptical fibers. In other embodiments they consist of single fiberoptics.

The assessment of translucency in accordance with embodiments of thepresent invention have already been described. It should be noted,however, that in accordance with the preferred embodiment both the lightreflected from the surface of the material/object (i.e., the peakingintensity) and its associated spectrum and the spectrum of the lightwhen it is in contact with the surface of the material/object may bemeasured/assessed. The two spectrums typically will differ in amplitude(the intensity or luminance typically will be greater above the surfacethan in contact with the surface) and the spectrums for certainmaterials may differ in chrominance (i.e., the structure of thespectrum) as well.

When a probe in accordance with such embodiments measures the peakingintensity, it in general is measuring both the light reflected from thesurface and light that penetrates the surface, gets bulk scatteredwithin the material and re-emerges from the material (e.g., the resultof translucency). When the probe is in contact with the surface (e.g.,less than the critical height), no light reflecting from the surface canbe detected by the receiver fiber optics, and thus any light detected bythe receivers is a result of the translucency of the material and itsspectrum is the result of scattering within the bulk of the material.The “reflected spectrum” and the “bulk spectrum” in general may bedifferent for different materials, and assessments of such reflected andbulk spectrum provide additional parameters for measuring, assessingand/or characterizing materials, surfaces, objects, teeth, etc., andprovide new mechanisms to distinguish translucent and other types ofmaterials.

In accordance with preferred embodiments of the present invention, anassessment or measurement of the degree of gloss (or specularreflection) may be made. For understanding thereof, reference is made toFIGS. 29 to 30B.

Referring to FIG. 29, consider two fiber optics, source fiber optic 460and receiver fiber optic 462, arranged perpendicular to a specularsurface as illustrated. The light reflecting from a purely specularsurface will be reflected in the form of a cone. As long as thenumerical aperture of the receiver fiber optic is greater than or equalto the numerical aperture of the source fiber optic, all the lightreflected from the surface that strikes the receiver fiber optic will bewithin the receiver fiber optic's acceptance cone and will be detected.In general, it does not matter what the numerical aperture of thereceiver fiber optic is, so long as it is greater than or equal to thenumerical aperture of the source fiber optic. When the fiber optic pairis far from the surface, receiver fiber optic 462 is fully illuminated.Eventually, as the pair approaches surface 464, receiver fiber optic 462is only partially illuminated. Eventually, at heights less than or equalto the critical height h_(c) receiver fiber optic 462 will not beilluminated. In general, such as for purely specular surfaces, it shouldbe noted that the critical height is a function of the numericalaperture of source fiber optic 460, and is not a function of thenumerical aperture of the receiver.

Referring now to FIGS. 30A and 30B, consider two fiber optics (source460 and receiver 462) perpendicular to diffuse surface 464A asillustrated in FIG. 30A (FIG. 30B depicts mixed specular/diffuse surface464B and area of intersection 466B). Source fiber optic 460 illuminatescircular area 466A on surface 464A, and the light is reflected fromsurface 464A. The light, however, will be reflected at all angles,unlike a specular surface where the light will only be reflected in theform of a cone. Receiver fiber optic 462 in general is alwaysilluminated at all heights, although it can only propagate and detectlight that strikes its surface at an angle less than or equal to itsacceptance angle. Thus, when the fiber optic pair is less than thecritical height, receiver fiber optic 462 detects no light. As theheight increases above the critical height, receiver fiber optic 462starts to detect light that originates from the area of intersection ofthe source and receiver cones as illustrated. Although light may beincident upon receiver fiber optic 462 from other areas of theilluminated circle, it is not detected because it is greater than theacceptance angle of the receiver fiber.

As the numerical aperture of receiver fiber optic 462 increases, theintensity detected by receiver fiber optic 462 will increase for diffusesurfaces, unlike a specular surface where the received intensity is nota function of receiver fiber optic numerical aperture. Thus, for a probeconstructed with a plurality of receiver fiber optics with differentnumerical apertures, as in preferred embodiments of the presentinvention, if the surface is a highly glossy surface, both receivers(see, e.g., receivers 456 and 458 of FIG. 28A, will measure the samelight intensity. As the surface becomes increasingly diffuse, howeverreceiver D 458 will have a greater intensity than receiver C 456. Theratio of the two intensities from receivers C/D is a measure of, orcorrelates to, the degree of specular reflection of the material, andmay be directly or indirectly used to quantify the “glossiness” of thesurface. Additionally, it should be noted that generally receiver C 456(preferably having the same numerical aperture as source fiber optic A452) measures principally the specular reflected component. Receiver D458, on the other hand, generally measures both diffuse and specularcomponents. As will be appreciated by those skilled in the art, suchprobes and methods utilizing receivers of different/varying numericalapertures may be advantageously utilized, with or without additionaloptical characteristic determinations as described elsewhere herein, tofurther quantify materials such as teeth or other objects.

Referring now to FIG. 31A, additional preferred embodiments will bedescribed. The embodiment of FIG. 31A utilizes very narrow numericalaperture, non-parallel fiber optic receivers 472 and very narrownumerical aperture source fiber optic 470 or utilizes other opticalelements to create collimated or nearly collimated source and receiverelements. Central source fiber optic 470 is a narrow numerical aperturefiber optic and receiver fiber optics 472 as illustrated (preferablymore than two such receivers are utilized in such embodiments) are alsonarrow fiber optics. Other receiver fiber optics may be wide numericalaperture fiber optics (e.g., receivers such as receivers 458 of FIG.28A). As illustrated, receiver fiber optics 472 of such embodiments areat an angle with respect to source fiber optic 470, with the numericalaperture of the receiver fiber optics selected such that, when thereceived intensity peaks as the probe is lowered to the surface, thereceiver fiber optics' acceptance cones intersect with the entirecircular area illuminated by the source fiber optic, or at least with asubstantial portion of the area illuminated by the source. Thus, thereceivers generally are measuring the same central spot illuminated bythe source fiber optic.

A particular aspect of such embodiments is that a specular excludedprobe/measurement technique may be provided. In general, the spectrallyreflected light is not incident upon the receiver fiber optics, and thusthe probe is only sensitive to diffuse light. Such embodiments may beuseful for coupling reflected light to a multi-band spectrometer (suchas described previously) or to more wide band sensors. Additionally,such embodiments may be useful as a part of a probe/measurementtechnique utilizing both specular included and specular excludedsensors. An illustrative arrangement utilizing such an arrangement isshown in FIG. 31B. In FIG. 31B, element 470 may consist of a sourcefiber optic, or alternatively may consist of all or part of the elementsshown in cross-section in FIGS. 28A or 28B. Still alternatively,non-parallel receiver fiber optics 472 may be parallel along theirlength but have a machined, polished, or other finished or other bentsurface on the end thereof in order to exclude all, or a substantial orsignificant portion, of the specularly reflected light. In otherembodiments, receiver fiber optics 472 may contain optical elementswhich exclude specularly reflected light. An additional aspect ofembodiments of the present invention is that they may be more fullyintegrated with an intraoral camera.

Referring now to FIGS. 32 to 34, various of such embodiments will bedescribed for illustrative purposes. In such embodiments, opticalcharacteristic measurement implements such as previously described maybe more closely integrated with an intraoral camera, including commonchassis 480, common cord or cable 482, and common probe 484. In one suchalternative preferred embodiment, camera optics 486 are positionedadjacent to spectrometer optics 488 near the end of probe 484, such asillustrated in FIG. 33. Spectrometer optics 488 may incorporate, forexample, elements of color and other optical characteristics measuringembodiments described elsewhere herein, such as shown in FIGS. 1-3,9-10B, 11-12, 20-21, 28A, 28B and 31A and 31B. In another embodiment,camera optics and lamp/light source 490 is positioned near the end ofprobe 484, around which are positioned a plurality of light receivers492. Camera optics and lamp/light source 490 provide illumination andoptics for the camera sensing element and a light source for makingcolor/optical characteristics in accordance with techniques describedelsewhere herein. It should be noted that light receivers 492 are shownas a single ring for illustrative purposes, although in otherembodiments light receivers such as described elsewhere herein (such asin the above-listed embodiments including multiple rings/groups, etc.)may be utilized in an analogous manner. Principles of such camera opticsgenerally are known in the borescope or endoscopes fields.

With respect to such embodiments, one instrument may be utilized forboth intraoral camera uses and for quantifying the optical properties ofteeth. The intraoral camera may be utilized for showing patients thegeneral state of the tooth, teeth or other dental health, or formeasuring certain properties of teeth or dental structure such as sizeand esthetics or for color postureization as previously described. Theoptical characteristic measuring implement may then measure the opticalproperties of the teeth such as previously described herein. In certainembodiments, such as illustrated in FIGS. 33 and 34, a protective shieldis placed over the camera for intraoral use in a conventional manner,and the protective shield is removed and a specialized tip is insertedinto spectrometer optics 488 or over camera optics and lamp/light source490 and light receivers 492 (such tips may be as discussed in connectionwith FIGS. 23A-23C, with a suitable securing mechanism) for infectioncontrol, thereby facilitating measuring and quantifying the opticalproperties. In other embodiments a common protective shield (preferablythin and tightly fitted, and optically transparent, such as are knownfor intraoral cameras) that covers both the camera portion andspectrometer portion are utilized.

Based on the foregoing embodiments, with which translucency and glossmay be measured or assessed, further aspects of the present inventionwill be described. As previously discussed, when light strikes anobject, it may be reflected from the surface, absorbed by the bulk ofthe material, or it may penetrate into the material and either beemitted from the surface or pass entirely through the material (i.e.,the result of translucency). Light reflected from the surface may beeither reflected specularly (i.e., the angle of reflection equals theangle of incidence), or it may be reflected diffusely (i.e., light maybe reflected at any angle). When light is reflected from a specularsurface, the reflected light tends to be concentrated. When it isreflected from a diffuse surface, the light tends to be distributed overan entire solid hemisphere (assuming the surface is planar) (see, e.g.,FIGS. 29-30B). Accordingly, if the receivers of such embodiments measureonly diffusely reflected light, the light spectrum (integrated spectrumor gray scale) will be less than an instrument that measures both thespecular and diffusely reflected light. Instruments that measure boththe specular and diffuse components may be referred to as “specularincluded” instruments, while those that measure only the diffusecomponent may be referred to as “specular excluded.”

An instrument that can distinguish and quantify the degree of gloss orthe ratio of specular to diffusely reflected light, such as withembodiments previously described, may be utilized in accordance with thepresent invention to correct and/or normalize a measured color spectrumto that of a standardized surface of the same color, such as a purelydiffuse or Lambertian surface. As will be apparent to one of skill inthe art, this may be done, for example, by utilizing the glossmeasurement to reduce the value or luminance of the color spectrum (theoverall intensity of the spectrum) to that of the perfectly diffusematerial.

A material that is translucent, on the other hand, tends to lower theintensity of the color spectrum of light reflected from the surface ofthe material. Thus, when measuring the color of a translucent material,the measured spectrum may appear darker than a similar colored materialthat is opaque. With translucency measurements made as previouslydescribed, such translucency measurements may be used to adjust themeasured color spectrum to that of a similar colored material that isopaque. As will be understood, in accordance with the present inventionthe measured color spectrum may be adjusted, corrected or normalizedbased on such gloss and/or translucency data, with the resulting datautilized, for example, for prosthesis preparation or other industrialutilization as described elsewhere herein.

Additional aspects of the present invention relating to the output ofoptical properties to a dental laboratory for prosthesis preparationwill now be described. There are many methods for quantifying color,including CIELab notation, Munsell notation, shade tab values, etc.Typically, the color of a tooth is reported by a dentist to the lab inthe form of a shade tab value. The nomenclature of the shade tab or itsvalue is an arbitrary number assigned to a particular standardized shadeguide. Dentists typically obtain the shade tabs from shade tabsuppliers. The labs utilize the shade tabs values in porcelain recipesto obtain the final color of the dental prosthesis.

Unfortunately, however, there are variances in the color of shade tabs,and there are variances in the color of batches of dental prosthesisceramics or other materials. Thus, there are variances in theceramics/material recipes to obtain a final color of a tooth resultingin a prosthesis that does not match the neighboring teeth.

In accordance with the present invention, such problems may be addressedas follows. A dental lab may receive a new batch of ceramic materialsand produce a test batch of materials covering desired color,translucency and/or gloss range(s). The test materials may then bemeasured, with values assigned to the test materials. The values andassociated color, translucency and gloss and other optical propertiesmay then be saved and stored, including into the dental instruments thatthe lab services (such as by modem download). Thereafter, when a dentistmeasures the optical properties of a patient's tooth, the output valuesfor the optical properties may be reported to the lab in a formula thatis directly related, or more desirably correlated, to the materials thatthe lab will utilize in order to prepare the prosthesis. Additionally,such functionality may enable the use of “virtual shade guides” or otherdata for customizing or configuring the instrument for the particularapplication.

Still other aspects of the present invention will be described withreference to FIGS. 35 and 36, which illustrate a cordless embodiment ofthe present invention. Cordless unit 500 includes a housing on which ismounted display 502 for display of color/optical property data or statusor other information. Keypad 504 is provided to input various commandsor information. Unit 500 also may be provided with control switch 510for initiating measurements or the like, along with speaker 512 foraudio feedback (such as previously described), wireless infrared serialtransceiver for wireless data transmission such as to an intelligentcharging stand (as hereinafter described) and/or to a host computer orthe like, battery compartment 516, serial port socket 518 (forconventional serial communications to an intelligent charging standand/or host computer, and/or battery recharging port 520. Unit 500includes probe 506, which in preferred embodiments may include removabletip 508 (such as previously described). Of course, unit 500 may containelements of the various embodiments as previously described herein.

Charging stand 526 preferably includes socket/holder 532 for holdingunit 500 while it is being recharged, and preferably includes a socketto connect to wired serial port 518, wireless IR serial transceiver 530,wired serial port 524 (such as an RS232 port) for connection to a hostcomputer (such as previously described), power cable 522 for providingexternal power to the system, and lamps 528 showing the charging stateof the battery and/or other status information or the like.

The system battery may be charged in charging stand 526 in aconventional manner. A charging indicator (such as lamps 528) may beused to provide an indication of the state of the internal battery. Unit500 may be removed from the stand, and an optical measurement may bemade by the dentist. If the dentist chooses, the optical measurement maybe read from display 502, and a prescription may be handwritten orotherwise prepared by the dentist. Alternately, the color/opticalcharacteristics data may be transmitted by wireless IR transceiver 514(or other cordless system such as RF) to a wireless transceiver, such astransceiver 530 of charging stand 526. The prescription may then beelectronically created based upon the color/optical characteristicsdata. The electronic prescription may be sent from serial port 524 to acomputer or modem or other communications channel to the dentallaboratory.

With reference to FIGS. 37A and 37B, additional aspects of the presentinvention will be discussed.

As is known, human teeth consist of an inner, generally opaque, dentinlayer, and an outer, generally translucent, enamel layer. As previouslydiscussed, light that is incident on a tooth generally can be affectedby the tooth in three ways. First, the light can be reflected from theouter surface of the tooth, either diffusely or specularly. Second, thelight can be internally scattered and absorbed by the tooth structures.Third, the light can be internally scattered and transmitted through thetooth structures and re-emerge from the surface of the tooth.Traditionally, it was difficult, if not impossible, to distinguish lightreflected from the surface of the tooth, whether specularly ordiffusely, from light that has penetrated the tooth, been scatteredinternally and re-emitted from the tooth. In accordance with the presentinvention, however, a differentiation may be made between light that isreflected from the surface of the tooth and light that is internallyscattered and re-emitted from the tooth.

As previously described, a critical height h_(c) occurs when a pair offiber optics serve to illuminate a surface or object and receive lightreflected from the surface or object. When the probe's distance from thetooth's surface is greater than the critical height h_(c) the receiverfiber optic is receiving light that is both reflected from the tooth'ssurface and light that is internally scattered and re-emitted by thetooth. When the distance of the probe is less than the critical heighth_(c), light that is reflected from the surface of the tooth no longercan be received by the received fiber optic. In general, the only lightthat can be accepted by the receiver fiber optic is light that haspenetrated enamel layer 540 and is re-emitted by the tooth (in caseswhere the object is a tooth).

Most of the internal light reflection and absorption within a toothoccurs at enamel-dentin interface or junction (DEJ) 542, which ingeneral separates enamel layer 540 from dentin 544. In accordance withthe present invention, an apparatus and method may be provided forquantifying optical properties of such sub-surface structures, such asthe color of DEJ 542, with or without comparison with data previouslytaken in order to facilitate the assessment or prediction of suchstructures.

Critical height h_(c) of the fiber optic probe such as previouslydescribed is a function of the fiber's numerical aperture and theseparation between the fibers. Thus, the critical height h_(c) of theprobe can be optimized based on the particular application. In addition,a probe may be constructed with multiple rings of receive fiber opticsand/or with multiple numerical aperture receiving fiber optics, therebyfacilitating assessment, etc., of enamel thickness, surface gloss, toothmorphology etc.

It is widely known that the thickness of the enamel layer of a toothvaries from the incisal edge to the cervical portion of the tooth crown,and from the middle of the tooth to the mesial and distal edges of thetooth (see FIGS. 37A and 37B, etc.). By utilizing multiple rings ofreceiver fiber optics, a measurement of the approximate thickness of theenamel layer may be made based on a comparison of the peak intensityabove the tooth surface and a measurement in contact with the toothsurface. A probe with multiple critical heights will give differentintensity levels when in contact with the tooth surface, therebyproducing data that may be indicative of the degree of internalscattering and enamel thickness or tooth morphology at the point ofcontact, etc.

Accordingly, in accordance with the present invention, the color orother optical characteristics of a sub-surface structure, such as DEJ542 of a tooth, may be assessed or quantified in a manner that is ingeneral independent of the optical characteristics of the surface of thetooth, and do so non-invasively, and do so in a manner that may alsoassess the thickness of the outer layer, such as enamel layer 540.

Additionally, and to emphasize the wide utility and variability ofvarious of the inventive concepts and techniques disclosed herein, itshould be apparent to those skilled in the art in view of thedisclosures herein that the apparatus and methodology may be utilized tomeasure the optical properties of objects/teeth using other opticalfocusing and gathering elements, in addition to the fiber opticsemployed in preferred embodiments herein. For example, lenses or mirrorsor other optical elements may also be utilized to construct both thelight source element and the light receiver element. A flashlight orother commonly available light source, as particular examples, may beutilized as the light source element, and a common telescope with aphotoreceiver may be utilized as the receiver element in a large scaleembodiment of the invention. Such refinements utilizing teachingsprovided herein are expressly within the scope of the present invention.

As will be apparent to those skilled in the art, certain refinements maybe made in accordance with the present invention. For example, a centrallight source fiber optic is utilized in certain preferred embodiments,but other light source arrangements (such as a plurality of light sourcefibers, etc.). In addition, lookup tables are utilized for variousaspects of the present invention, but polynomial type calculations couldsimilarly be employed. Thus, although various preferred embodiments ofthe present invention have been disclosed for illustrative purposes,those skilled in the art will appreciate that various modifications,additions and/or substitutions are possible without departing from thescope and spirit of the present invention as disclosed in the claims. Inaddition, while various embodiments utilize light principally in thevisible light spectrum, the present invention is not necessarily limitedto all or part of such visible light spectrum, and may include radiantenergy not within such visible light spectrum.

Reference is made to copending application filed on even date herewithfor Apparatus and Method for Measuring Optical Characteristics of anObject, and for Method and Apparatus for Detecting and PreventingCounterfeiting, both by the inventors hereof, which is herebyincorporated by reference.

What is claimed is:
 1. A method comprising the steps of: moving a probein proximity to an object through relative movement between the probeand the object, wherein the probe provides light to the object from oneor more light sources, and receives light from the object through aplurality of light receivers, wherein the plurality of light receiverscomprise one or more first light receivers and one or more second lightreceivers, wherein the one or more first light receivers have a firstnumerical aperture and the one or more second light receivers have asecond numerical aperture different from the first numerical aperture;determining the intensity of light received by more than one of thelight receivers; and measuring the optical characteristics of theobject, wherein the measurement produces data indicative of the opticalcharacteristics of the object and includes at least first and secondmeasurements with the probe at first and second distances from theobject; wherein light from the one or more of the first or second lightreceivers is coupled to one or more sensors, wherein the one or moresensors generate at least one signal having a frequency proportional tothe light intensity received by the one or more sensors.
 2. The methodof claim 1, wherein the optical characteristics of the object comprisecolor characteristics.
 3. The method of claim 1, wherein the opticalcharacteristics of the object comprise translucence characteristics. 4.The method of claim 1, wherein the optical characteristics of the objectcomprise fluorescence characteristics.
 5. The method of claim 1, whereinthe optical characteristics of the object comprise surface texturecharacteristics.
 6. The method of claim 1, wherein the opticalcharacteristics of the object comprise gloss characteristics.
 7. Amethod comprising the steps of: moving a probe towards an object throughrelative movement between the probe and the object, wherein light isemitted by the probe onto the object, and light is received from theobject by the probe; during the step of moving the probe towards theobject, taking one or more first measurements; when the probe is nearthe object, taking one or more second measurements; based on the firstand second measurements, determining optical characteristics of theobject including one or more of the characteristics of the groupconsisting of reflected surface color spectrum, bulk material colorspectrum, gloss, translucency, fluorescence, and surface texture;wherein, as part of the first and/or second measurements, light iscoupled to one or more sensors, wherein the one or more sensors generateat least one signal having a frequency proportional to the lightintensity received by the one or more sensors.
 8. The method of claim 7,wherein the probe includes one or more light sources and at least twotypes of light receivers, wherein the first type of light receivers havea first numerical aperture and the second type of light receivers have asecond numerical aperture.
 9. The method of claim 7, further comprisingthe step of preparing a second object based on the determined opticalcharacteristics.
 10. The method of claim 7, further comprising the stepof transmitting data indicative of the determined opticalcharacteristics to a remote location, and preparing a second objectbased on the determined optical characteristics at the remote location.11. The method of claim 7, further comprising the steps of: generatingfirst data corresponding to characteristics of the type of object beingmeasured; comparing the first data with the determined opticalcharacteristics; and assessing a condition of the object based on thecomparison.
 12. The method of claim 11, wherein the condition comprisesa condition relating to a subsurface feature of the object.
 13. Themethod of claim 7, wherein color spectrum data is adjusted based ondetermined gloss data.
 14. The method of claim 7, wherein color spectrumdata is adjusted based on determined translucency data.
 15. The methodof claim 7, wherein color spectrum data is adjusted based on determinedgloss and translucency data.
 16. A method comprising the steps of:moving a probe towards an object through relative movement between theprobe and the object, wherein light from one or more light sources isdirected from the probe to the object; during the step of moving theprobe towards the object, taking first measurements; when the probe isnear the object, taking second measurements; based on the first andsecond measurements, determining optical characteristics of the objectincluding one or more of the characteristics of the group consisting ofreflected surface color spectrum, bulk material color spectrum, gloss,translucency, fluorescence, and surface texture; and storing dataindicative of the determined optical characteristics in a data base;wherein, as part of the first and/or second measurements, light iscoupled to one or more sensors, wherein the one or more sensors generateat least one signal having a frequency proportional to the lightintensity received by the one or more sensors.
 17. The method of claim16, further comprising the steps of: capturing an image of the objectwith a camera; and storing the captured image in the data base.
 18. Themethod of claim 17, further comprising the step of correlating the dataindicative of the determined optical characteristics with the capturedimage, wherein the captured image includes indicia of the location atwhich the optical characteristics were determined.
 19. The method ofclaim 17, further comprising the steps of: postureizing the object intoat least first and second regions; determining optical characteristicsof the object in the first and second regions; correlating dataindicative of the determined optical characteristics in the first andsecond regions with the captured image, wherein the captured imageincludes indicia of the first and second regions.
 20. The method ofclaim 19, further comprising the step of preparing a second object basedon the determined optical characteristics.
 21. The method of claim 19,further comprising the step of transmitting data indicative of thedetermined optical characteristics to a remote location, and preparing asecond object based on the determined optical characteristics at theremote location.
 22. The method of claim 17, wherein the camera ispositioned in the probe.
 23. The method of claim 17, wherein the lightsource and light receivers comprise fiber optics.
 24. The method ofclaim 16, wherein the object comprises a dental object.
 25. The methodof claim 16, wherein the probe is coupled to a dental chair adapted tohold the probe during a time when the probe is not taking measurements.26. The method of claim 16, wherein the probe includes a removable tip.27. The method of claim 16, wherein the probe is covered by a removableshield.
 28. The method of claim 27, wherein the shield is disposable.29. The method of claim 16, wherein data indicative of the determinedoptical characteristics is coupled to a material preparation device,wherein the material preparation device prepares materials based on thedetermined optical characteristics.
 30. The method of claim 16, whereinthe determined optical characteristics include a specular-includedspectrum and a specular-excluded spectrum, wherein the specular-includedspectrum substantially includes light specularly reflected from theobject, and wherein the specular-excluded substantially excludes lightspecularly reflected from the object.
 31. A method comprising the stepsof: moving a probe towards an object through relative movement betweenthe probe and the object, wherein light from one or more light sourcesis emitted from the probe to the object; receiving light from the objectwith a plurality of light receivers on the probe, wherein the receivershave numerical apertures and sizes sufficient to receive lightindicative of a specular-included spectrum and a specular-excludedspectrum, wherein the specular-included spectrum substantially includeslight specularly reflected from the object, and wherein thespecular-excluded substantially excludes light specularly reflected fromthe object; wherein light from one or more of the light receivers iscoupled to one or more sensors, wherein the one or more sensors generateat least one signal having a frequency proportional to the lightintensity received by the one or more sensors.
 32. An apparatus formeasuring optical characteristics of an object with a probe as the probeis moved towards the object through relative movement between the probeand the object, comprising: a probe having one or more light sources anda plurality of light receivers, wherein the probe provides light to thesurface of the object from the one or more light sources, and receiveslight from the object through the plurality of light receivers, whereinthe plurality of light receivers comprise one or more first lightreceivers and one or more second light receivers, wherein the one ormore first light receivers have a first numerical aperture and the oneor more second light receivers have a second numerical aperturedifferent from the first numerical aperture; sensors coupled to receivelight from the light receivers, wherein one or more sensors of thesensors generate at least one signal having a frequency proportional tothe light intensity received by the one or more sensors; a processorcoupled to receive data from the sensors; wherein the processor makes aplurality of measurements and determines data indicative of the opticalcharacteristics of the object based on the data received from thesensors, wherein the measurements include at least first and secondmeasurements with the probe at first and second distances from theobject.
 33. The apparatus of claim 32, wherein the opticalcharacteristics of the object comprise color characteristics.
 34. Theapparatus of claim 32, wherein the optical characteristics of the objectcomprise translucence characteristics.
 35. The apparatus of claim 32,wherein the optical characteristics of the object comprise fluorescencecharacteristics.
 36. The apparatus of claim 32, wherein the opticalcharacteristics of the object comprise surface texture characteristics.37. The apparatus of claim 32, wherein the optical characteristics ofthe object comprise gloss characteristics.
 38. The apparatus of claim32, wherein the one or more light sources and plurality of lightreceivers comprise fiber optics.
 39. The apparatus of claim 32, wherein,during the movement of the probe towards the object, the processor takesfirst measurements, and when the probe is near the object, the processortakes second measurements; wherein, based on the first and secondmeasurements, the processor determines data indicative of the opticalcharacteristics of the object including one or more of thecharacteristics of the group consisting of reflected surface colorspectrum, bulk material color spectrum, gloss, translucency,fluorescence, and surface texture.
 40. The apparatus of claim 32,wherein the data indicative of the optical characteristics of the objectare coupled to a device for preparing a second object based on thedetermined optical characteristics.
 41. The apparatus of claim 32,further means for transmitting data indicative of the determined opticalcharacteristics to a remote location, wherein a second object based onthe determined optical characteristics is prepared at the remotelocation.
 42. The apparatus of claim 32, wherein the processor comparesthe determined optical characteristics with first data corresponding tocharacteristics of the type of object being measured, and the processorassesses a condition of the object based on the comparison.
 43. Theapparatus of claim 42, wherein the condition comprises a conditionrelating to a subsurface feature of the object.
 44. The apparatus ofclaim 42, further comprising an audio circuit for providing audioinformation, wherein the audio information provides informationregarding the operation or status of the probe.
 45. The apparatus ofclaim 42, further comprising an audio circuit for providing audioinformation, wherein the audio information provides informationregarding the status of the optical characteristics determinationprocess.
 46. A method comprising the steps of: moving a probe towards anobject through relative movement between the probe and the object,wherein light from one or more light sources is emitted from the probeto the object; receiving light from the object with a plurality of lightreceivers on the probe, wherein the receivers have numerical aperturesand sizes to receive light indicative of a specular-included spectrumand a specular-only spectrum, wherein the specular-included spectrumsubstantially includes light specularly and diffusely reflected from theobject, and wherein the specular-only spectrum substantially consists oflight specularly reflected from the object; wherein light from one ormore of the light receivers is coupled to one or more sensors, whereinthe one or more sensors generate at least one signal having a frequencyproportional to the light intensity received by the one or more sensors.47. A method of quantifying the color of an object comprising the stepsof positioning a probe near the object, wherein light from one or morelight sources is emitted from the probe to the object, and receivinglight from the object with a plurality of light receivers on the probeof at least two different numerical apertures, wherein a reflected colorspectrum of the object is measured and translucency and gloss of theobject are measured, wherein the translucency and gloss measurement areused to adjust the color spectrum measurement to compensate fortranslucency and gloss of the object; wherein light from one or more ofthe light receivers is coupled to one or more sensors, wherein the oneor more sensors generate at least one signal having a frequencyproportional to the light intensity received by the one or more sensors.48. A method of quantifying the color of an object comprising the stepsof positioning a probe near the object, wherein light from one or morelight sources is emitted from the probe to the object, and receivinglight from the object with a plurality of light receivers on the probeof at least two different numerical apertures, wherein a reflected colorspectrum of the object is measured and gloss of the object is measured,wherein the gloss measurement is used to adjust the color spectrummeasurement to compensate for gloss of the object; wherein light fromone or more of the light receivers is coupled to one or more sensors,wherein the one or more sensors generate at least one signal having afrequency proportional to the light intensity received by the one ormore sensors.
 49. The method of claim 1, wherein the at least one signalcomprises a digital signal.
 50. The method of claim 49, wherein thedigital signal comprises a TTL or CMOS digital signal.
 51. The method ofclaim 1, wherein the light passes through a filter prior to beingcoupled to one or more of the sensors, wherein the opticalcharacteristics are measured based on measuring a period of a pluralityof digital signals produced by a plurality of sensors.
 52. The method ofclaim 1, wherein the signal comprises an asynchronous signal of afrequency dependent upon the intensity of the received light.
 53. Themethod of claim 1, wherein the one or more sensors comprise a pluralityof light to frequency converter sensing elements.
 54. The method ofclaim 1, wherein the light passes through a filter prior to beingcoupled to one or more of the sensors, wherein the filter comprises aplurality of filter portions having a wavelength dependent opticaltransmission property.
 55. The method of claim 1, wherein the opticalcharacteristics comprise a spectral analysis based on light receivedfrom the object.
 56. The method of claim 1, wherein the light passesthrough a filter prior to being coupled to one or more of the sensors,wherein the filter comprises a plurality of cut-off filter elements. 57.The method of claim 1, wherein the light passes through a filter priorto being coupled to one or more of the sensors, wherein the filtercomprises a filter grid.
 58. The method of claim 1, wherein the lightpasses through a filter prior to being coupled to one or more of thesensors, wherein the received light is spectrally analyzed without usinga diffraction grating.
 59. The method of claim 7, wherein the first andsecond measurements include measurements with the probe at first andsecond distances from the object.
 60. The method of claim 7, wherein theat least one signal comprises a digital signal.
 61. The method of claim60, wherein the digital signal comprises a TTL or CMOS digital signal.62. The method of claim 7, wherein the light passes through a filterprior to being coupled to one or more of the sensors, wherein theoptical characteristics are determined based on measuring a period of aplurality of digital signals produced by a plurality of sensors.
 63. Themethod of claim 7, wherein the signal comprises an asynchronous signalof a frequency dependent upon the intensity of the received light. 64.The method of claim 7, wherein the one or more sensors comprise aplurality of light to frequency converter sensing elements.
 65. Themethod of claim 7, wherein the light passes through a filter prior tobeing coupled to one or more of the sensors, wherein the filtercomprises a plurality of filter portions having a wavelength dependentoptical transmission property.
 66. The method of claim 7, wherein theoptical characteristics comprise a spectral analysis based on lightreceived from the object.
 67. The method of claim 7, wherein the lightpasses through a filter prior to being coupled to one or more of thesensors, wherein the filter comprises a plurality of cut-off filterelements.
 68. The method of claim 7, wherein the light passes through afilter prior to being coupled to one or more of the sensors, wherein thefilter comprises a filter grid.
 69. The method of claim 7, wherein thelight passes through a filter prior to being coupled to one or more ofthe sensors, wherein the received light is spectrally analyzed withoutusing a diffraction grating.
 70. The method of claim 16, wherein thefirst and second measurements include measurements with the probe atfirst and second distances from the object.
 71. The method of claim 16,wherein the at least one signal comprises a digital signal.
 72. Themethod of claim 71, wherein the digital signal comprises a TTL or CMOSdigital signal.
 73. The method of claim 16, wherein the light passesthrough a filter prior to being coupled to one or more of the sensors,wherein the optical characteristics are determined based on measuring aperiod of a plurality of digital signals produced by a plurality ofsensors.
 74. The method of claim 16, wherein the signal comprises anasynchronous signal of a frequency dependent upon the intensity of thereceived light.
 75. The method of claim 16, wherein the one or moresensors comprise a plurality of light to frequency converter sensingelements.
 76. The method of claim 16, wherein the light passes through afilter prior to being coupled to one or more of the sensors, wherein thefilter comprises a plurality of filter portions having a wavelengthdependent optical transmission property.
 77. The method of claim 16,wherein the optical characteristics comprise a spectral analysis basedon light received from the object.
 78. The method of claim 16, whereinthe light passes through a filter prior to being coupled to one or moreof the sensors, wherein the filter comprises a plurality of cut-offfilter elements.
 79. The method of claim 16, wherein the light passesthrough a filter prior to being coupled to one or more of the sensors,wherein the filter comprises a filter grid.
 80. The method of claim 16,wherein the light passes through a filter prior to being coupled to oneor more of the sensors, wherein the received light is spectrallyanalyzed without using a diffraction grating.
 81. The method of claim31, wherein at least first and second measurements are taken with theprobe at first and second distances from the object.
 82. The method ofclaim 31, wherein the at least one signal comprises a digital signal.83. The method of claim 82, wherein the digital signal comprises a TTLor CMOS digital signal.
 84. The method of claim 31, wherein the lightpasses through a filter prior to being coupled to one or more of thesensors, wherein an optical characteristic is measured based onmeasuring a period of a plurality of digital signals produced by aplurality of sensors.
 85. The method of claim 31, wherein the signalcomprises an asynchronous signal of a frequency dependent upon theintensity of the received light.
 86. The method of claim 31, wherein theone or more sensors comprise a plurality of light to frequency convertersensing elements.
 87. The method of claim 31, wherein the light passesthrough a filter prior to being coupled to one or more of the sensors,wherein the filter comprises a plurality of filter portions having awavelength dependent optical transmission property.
 88. The method ofclaim 31, wherein a measured characteristic of the object comprises aspectral analysis based on light received from the object.
 89. Themethod of claim 31, wherein the light passes through a filter prior tobeing coupled to one or more of the sensors, wherein the filtercomprises a plurality of cut-off filter elements.
 90. The method ofclaim 31, wherein the light passes through a filter prior to beingcoupled to one or more of the sensors, wherein the filter comprises afilter grid.
 91. The method of claim 31, wherein the light passesthrough a filter prior to being coupled to one or more of the sensors,wherein the received light is spectrally analyzed without using adiffraction grating.
 92. The apparatus of claim 32, wherein the at leastone signal comprises a digital signal.
 93. The apparatus of claim 92,wherein the digital signal comprises a TTL or CMOS digital signal. 94.The apparatus of claim 32, wherein the light passes through a filterprior to being coupled to one or more of the sensors, wherein theoptical characteristics are measured based on measuring a period of aplurality of digital signals produced by a plurality of sensors.
 95. Theapparatus of claim 32, wherein the signal comprises an asynchronoussignal of a frequency dependent upon the intensity of the receivedlight.
 96. The apparatus of claim 32, wherein the one or more sensorscomprise a plurality of light to frequency converter sensing elements.97. The apparatus of claim 32, wherein the light passes through a filterprior to being coupled to one or more of the sensors, wherein the filtercomprises a plurality of filter portions having a wavelength dependentoptical transmission property.
 98. The apparatus of claim 32, whereinthe optical characteristics comprise a spectral analysis based on lightreceived from the object.
 99. The apparatus of claim 32, wherein thelight passes through a filter prior to being coupled to one or more ofthe sensors, wherein the filter comprises a plurality of cut-off filterelements.
 100. The apparatus of claim 32, wherein the light passesthrough a filter prior to being coupled to one or more of the sensors,wherein the filter comprises a filter grid.
 101. The apparatus of claim32, wherein the light passes through a filter prior to being coupled toone or more of the sensors, wherein the received light is spectrallyanalyzed without using a diffraction grating.
 102. The method of claim46, wherein at least first and second measurements are taken with theprobe at first and second distances from the object.
 103. The method ofclaim 46, wherein the at least one signal comprises a digital signal.104. The method of claim 103, wherein the digital signal comprises a TTLor CMOS digital signal.
 105. The method of claim 46, wherein the lightpasses through a filter prior to being coupled to one or more of thesensors, wherein an optical characteristic is measured based onmeasuring a period of a plurality of digital signals produced by aplurality of sensors.
 106. The method of claim 46, wherein the signalcomprises an asynchronous signal of a frequency dependent upon theintensity of the received light.
 107. The method of claim 46, whereinthe one or more sensors comprise a plurality of light to frequencyconverter sensing elements.
 108. The method of claim 46, wherein thelight passes through a filter prior to being coupled to one or more ofthe sensors, wherein the filter comprises a plurality of filter portionshaving a wavelength dependent optical transmission property.
 109. Themethod of claim 46, wherein a measured characteristic comprises aspectral analysis based on light received from the object.
 110. Themethod of claim 46, wherein the light passes through a filter prior tobeing coupled to one or more of the sensors, wherein the filtercomprises a plurality of cut-off filter elements.
 111. The method ofclaim 46, wherein the light passes through a filter prior to beingcoupled to one or more of the sensors, wherein the filter comprises afilter grid.
 112. The method of claim 46, wherein the light passesthrough a filter prior to being coupled to one or more of the sensors,wherein the received light is spectrally analyzed without using adiffraction grating.
 113. The method of claim 47, wherein at least firstand second measurements are taken with the probe at first and seconddistances from the object.
 114. The method of claim 47, wherein the atleast one signal comprises a digital signal.
 115. The method of claim114, wherein the digital signal comprises a TTL or CMOS digital signal.116. The method of claim 47, wherein the light passes through a filterprior to being coupled to one or more of the sensors, wherein an opticalcharacteristic is measured based on measuring a period of a plurality ofdigital signals produced by a plurality of sensors.
 117. The method ofclaim 47, wherein the signal comprises an asynchronous signal of afrequency dependent upon the intensity of the received light.
 118. Themethod of claim 47, wherein the one or more sensors comprise a pluralityof light to frequency converter sensing elements.
 119. The method ofclaim 47, wherein the light passes through a filter prior to beingcoupled to one or more of the sensors, wherein the filter comprises aplurality of filter portions having a wavelength dependent opticaltransmission property.
 120. The method of claim 47, wherein a measuredcharacteristic comprises a spectral analysis based on light receivedfrom the object.
 121. The method of claim 47, wherein the light passesthrough a filter prior to being coupled to one or more of the sensors,wherein the filter comprises a plurality of cut-off filter elements.122. The method of claim 47, wherein the light passes through a filterprior to being coupled to one or more of the sensors, wherein the filtercomprises a filter grid.
 123. The method of claim 47, wherein the lightpasses through a filter prior to being coupled to one or more of thesensors, wherein the received light is spectrally analyzed without usinga diffraction grating.
 124. The method of claim 48, wherein at leastfirst and second measurements are taken with the probe at first andsecond distances from the object.
 125. The method of claim 48, whereinthe at least one signal comprises a digital signal.
 126. The method ofclaim 125, wherein the digital signal comprises a TTL or CMOS digitalsignal.
 127. The method of claim 48, wherein the light passes through afilter prior to being coupled to one or more of the sensors, wherein anoptical characteristic is measured based on measuring a period of aplurality of digital signals produced by a plurality of sensors. 128.The method of claim 48, wherein the signal comprises an asynchronoussignal of a frequency dependent upon the intensity of the receivedlight.
 129. The method of claim 48, wherein the one or more sensorscomprise a plurality of light to frequency converter sensing elements.130. The method of claim 48, wherein the light passes through a filterprior to being coupled to one or more of the sensors, wherein the filtercomprises a plurality of filter portions having a wavelength dependentoptical transmission property.
 131. The method of claim 48, wherein ameasured characteristic comprises a spectral analysis based on lightreceived from the object.
 132. The method of claim 48, wherein the lightpasses through a filter prior to being coupled to one or more of thesensors, wherein the filter comprises a plurality of cut-off filterelements.
 133. The method of claim 48, wherein the light passes througha filter prior to being coupled to one or more of the sensors, whereinthe filter comprises a filter grid.
 134. The method of claim 48, whereinthe light passes through a filter prior to being coupled to one or moreof the sensors, wherein the received light is spectrally analyzedwithout using a diffraction grating.